Use single callback for replies to async operations Single callback simplifies copying of callbacks and makes control flow more obvious. BUG:24267885 Change-Id: I489e7158e2bb1adf8c9c3966a0859fa024a57db2 Reviewed-on: https://weave-review.googlesource.com/1302 Reviewed-by: Vitaly Buka <vitalybuka@google.com>

diff --git a/libweave/examples/ubuntu/curl_http_client.cc b/libweave/examples/ubuntu/curl_http_client.cc
index c058a9b..653cbb3 100644
--- a/libweave/examples/ubuntu/curl_http_client.cc
+++ b/libweave/examples/ubuntu/curl_http_client.cc

@@ -35,18 +35,11 @@
 CurlHttpClient::CurlHttpClient(provider::TaskRunner* task_runner)
     : task_runner_{task_runner} {}
 
-void CurlHttpClient::PostError(const ErrorCallback& error_callback,
-                               ErrorPtr error) {
-  task_runner_->PostDelayedTask(
-      FROM_HERE, base::Bind(error_callback, base::Passed(&error)), {});
-}
-
 void CurlHttpClient::SendRequest(Method method,
                                  const std::string& url,
                                  const Headers& headers,
                                  const std::string& data,
-                                 const SuccessCallback& success_callback,
-                                 const ErrorCallback& error_callback) {
+                                 const SendRequestCallback& callback) {
   std::unique_ptr<CURL, decltype(&curl_easy_cleanup)> curl{curl_easy_init(),
                                                            &curl_easy_cleanup};
   CHECK(curl);
@@ -96,7 +89,8 @@
   if (res != CURLE_OK) {
     Error::AddTo(&error, FROM_HERE, "curl", "curl_easy_perform_error",
                  curl_easy_strerror(res));
-    return PostError(error_callback, std::move(error));
+    return task_runner_->PostDelayedTask(
+        FROM_HERE, base::Bind(callback, nullptr, base::Passed(&error)), {});
   }
 
   const std::string kContentType = "\r\nContent-Type:";
@@ -104,7 +98,8 @@
   if (pos == std::string::npos) {
     Error::AddTo(&error, FROM_HERE, "curl", "no_content_header",
                  "Content-Type header is missing");
-    return PostError(error_callback, std::move(error));
+    return task_runner_->PostDelayedTask(
+        FROM_HERE, base::Bind(callback, nullptr, base::Passed(&error)), {});
   }
   pos += kContentType.size();
   auto pos_end = response->content_type.find("\r\n", pos);
@@ -118,15 +113,7 @@
                                        &response->status));
 
   task_runner_->PostDelayedTask(
-      FROM_HERE, base::Bind(&CurlHttpClient::RunSuccessCallback,
-                            weak_ptr_factory_.GetWeakPtr(), success_callback,
-                            base::Passed(&response)),
-      {});
-}
-
-void CurlHttpClient::RunSuccessCallback(const SuccessCallback& success_callback,
-                                        std::unique_ptr<Response> response) {
-  success_callback.Run(*response);
+      FROM_HERE, base::Bind(callback, base::Passed(&response), nullptr), {});
 }
 
 }  // namespace examples

diff --git a/libweave/examples/ubuntu/curl_http_client.h b/libweave/examples/ubuntu/curl_http_client.h
index a5090ff..6bbb3f4 100644
--- a/libweave/examples/ubuntu/curl_http_client.h
+++ b/libweave/examples/ubuntu/curl_http_client.h

@@ -28,14 +28,9 @@
                    const std::string& url,
                    const Headers& headers,
                    const std::string& data,
-                   const SuccessCallback& success_callback,
-                   const ErrorCallback& error_callback) override;
+                   const SendRequestCallback& callback) override;
 
  private:
-  void PostError(const ErrorCallback& error_callback, ErrorPtr error);
-
-  void RunSuccessCallback(const SuccessCallback& success_callback,
-                          std::unique_ptr<Response> response);
   provider::TaskRunner* task_runner_{nullptr};
 
   base::WeakPtrFactory<CurlHttpClient> weak_ptr_factory_{this};

diff --git a/libweave/examples/ubuntu/event_http_client.cc b/libweave/examples/ubuntu/event_http_client.cc
index 8341a07..637ae2f 100644
--- a/libweave/examples/ubuntu/event_http_client.cc
+++ b/libweave/examples/ubuntu/event_http_client.cc

@@ -60,8 +60,7 @@
   TaskRunner* task_runner_;
   std::unique_ptr<evhttp_uri, EventDeleter> http_uri_;
   std::unique_ptr<evhttp_connection, EventDeleter> evcon_;
-  HttpClient::SuccessCallback success_callback_;
-  ErrorCallback error_callback_;
+  HttpClient::SendRequestCallback callback_;
 };
 
 void RequestDoneCallback(evhttp_request* req, void* ctx) {
@@ -74,7 +73,7 @@
                        "request failed: %s",
                        evutil_socket_error_to_string(err));
     state->task_runner_->PostDelayedTask(
-        FROM_HERE, base::Bind(state->error_callback_, base::Passed(&error)),
+        FROM_HERE, base::Bind(state->callback_, nullptr, base::Passed(&error)),
         {});
     return;
   }
@@ -86,7 +85,8 @@
   auto n = evbuffer_remove(buffer, &response->data[0], length);
   CHECK_EQ(n, int(length));
   state->task_runner_->PostDelayedTask(
-      FROM_HERE, base::Bind(state->success_callback_, *response), {});
+      FROM_HERE, base::Bind(state->callback_, base::Passed(&response), nullptr),
+      {});
 }
 
 }  // namespace
@@ -98,8 +98,7 @@
                                   const std::string& url,
                                   const Headers& headers,
                                   const std::string& data,
-                                  const SuccessCallback& success_callback,
-                                  const ErrorCallback& error_callback) {
+                                  const SendRequestCallback& callback) {
   evhttp_cmd_type method_id;
   CHECK(weave::StringToEnum(weave::EnumToString(method), &method_id));
   std::unique_ptr<evhttp_uri, EventDeleter> http_uri{
@@ -129,7 +128,7 @@
   std::unique_ptr<evhttp_request, EventDeleter> req{evhttp_request_new(
       &RequestDoneCallback,
       new EventRequestState{task_runner_, std::move(http_uri), std::move(conn),
-                            success_callback, error_callback})};
+                            callback})};
   CHECK(req);
   auto output_headers = evhttp_request_get_output_headers(req.get());
   evhttp_add_header(output_headers, "Host", host);
@@ -150,7 +149,7 @@
                      "request failed: %s %s", EnumToString(method).c_str(),
                      url.c_str());
   task_runner_->PostDelayedTask(
-      FROM_HERE, base::Bind(error_callback, base::Passed(&error)), {});
+      FROM_HERE, base::Bind(callback, nullptr, base::Passed(&error)), {});
 }
 
 }  // namespace examples

diff --git a/libweave/examples/ubuntu/event_http_client.h b/libweave/examples/ubuntu/event_http_client.h
index 457e550..e564e8a 100644
--- a/libweave/examples/ubuntu/event_http_client.h
+++ b/libweave/examples/ubuntu/event_http_client.h

@@ -24,8 +24,7 @@
                    const std::string& url,
                    const Headers& headers,
                    const std::string& data,
-                   const SuccessCallback& success_callback,
-                   const ErrorCallback& error_callback) override;
+                   const SendRequestCallback& callback) override;
 
  private:
   EventTaskRunner* task_runner_{nullptr};

diff --git a/libweave/examples/ubuntu/main.cc b/libweave/examples/ubuntu/main.cc
index e762791..6324411 100644
--- a/libweave/examples/ubuntu/main.cc
+++ b/libweave/examples/ubuntu/main.cc

@@ -221,12 +221,11 @@
   base::WeakPtrFactory<CommandHandler> weak_ptr_factory_{this};
 };
 
-void RegisterDeviceSuccess(weave::Device* device) {
-  LOG(INFO) << "Device registered: " << device->GetSettings().cloud_id;
-}
-
-void RegisterDeviceError(weave::ErrorPtr error) {
-  LOG(ERROR) << "Fail to register device: " << error->GetMessage();
+void OnRegisterDeviceDone(weave::Device* device, weave::ErrorPtr error) {
+  if (error)
+    LOG(ERROR) << "Fail to register device: " << error->GetMessage();
+  else
+    LOG(INFO) << "Device registered: " << device->GetSettings().cloud_id;
 }
 
 }  // namespace
@@ -280,8 +279,7 @@
 
   if (!registration_ticket.empty()) {
     device->Register(registration_ticket,
-                     base::Bind(&RegisterDeviceSuccess, device.get()),
-                     base::Bind(&RegisterDeviceError));
+                     base::Bind(&OnRegisterDeviceDone, device.get()));
   }
 
   CommandHandler handler(device.get(), &task_runner);

diff --git a/libweave/examples/ubuntu/netlink_network.cc b/libweave/examples/ubuntu/netlink_network.cc
index 24d0996..60807a4 100644
--- a/libweave/examples/ubuntu/netlink_network.cc
+++ b/libweave/examples/ubuntu/netlink_network.cc

@@ -91,23 +91,22 @@
   return network_state_;
 }
 
-void NetlinkNetworkImpl::OpenSslSocket(
-    const std::string& host,
-    uint16_t port,
-    const OpenSslSocketSuccessCallback& success_callback,
-    const ErrorCallback& error_callback) {
+void NetlinkNetworkImpl::OpenSslSocket(const std::string& host,
+                                       uint16_t port,
+                                       const OpenSslSocketCallback& callback) {
   // Connect to SSL port instead of upgrading to TLS.
   std::unique_ptr<SSLStream> tls_stream{new SSLStream{task_runner_}};
 
   if (tls_stream->Init(host, port)) {
     task_runner_->PostDelayedTask(
-        FROM_HERE, base::Bind(success_callback, base::Passed(&tls_stream)), {});
+        FROM_HERE, base::Bind(callback, base::Passed(&tls_stream), nullptr),
+        {});
   } else {
     ErrorPtr error;
     Error::AddTo(&error, FROM_HERE, "tls", "tls_init_failed",
                  "Failed to initialize TLS stream.");
     task_runner_->PostDelayedTask(
-        FROM_HERE, base::Bind(error_callback, base::Passed(&error)), {});
+        FROM_HERE, base::Bind(callback, nullptr, base::Passed(&error)), {});
   }
 }
 

diff --git a/libweave/examples/ubuntu/netlink_network.h b/libweave/examples/ubuntu/netlink_network.h
index 3f5f51a..af8bf13 100644
--- a/libweave/examples/ubuntu/netlink_network.h
+++ b/libweave/examples/ubuntu/netlink_network.h

@@ -29,8 +29,7 @@
   State GetConnectionState() const override;
   void OpenSslSocket(const std::string& host,
                      uint16_t port,
-                     const OpenSslSocketSuccessCallback& success_callback,
-                     const ErrorCallback& error_callback) override;
+                     const OpenSslSocketCallback& callback) override;
 
  private:
   class Deleter {

diff --git a/libweave/examples/ubuntu/network_manager.cc b/libweave/examples/ubuntu/network_manager.cc
index ff54f0b..e6dd9d8 100644
--- a/libweave/examples/ubuntu/network_manager.cc
+++ b/libweave/examples/ubuntu/network_manager.cc

@@ -61,8 +61,7 @@
                                const std::string& passphrase,
                                int pid,
                                base::Time until,
-                               const SuccessCallback& success_callback,
-                               const ErrorCallback& error_callback) {
+                               const DoneCallback& callback) {
   if (pid) {
     int status = 0;
     if (pid == waitpid(pid, &status, WNOWAIT)) {
@@ -79,7 +78,8 @@
       close(sockf_d);
 
       if (ssid == essid)
-        return task_runner_->PostDelayedTask(FROM_HERE, success_callback, {});
+        return task_runner_->PostDelayedTask(FROM_HERE,
+                                             base::Bind(callback, nullptr), {});
       pid = 0;  // Try again.
     }
   }
@@ -94,34 +94,32 @@
     Error::AddTo(&error, FROM_HERE, "wifi", "timeout",
                  "Timeout connecting to WiFI network.");
     task_runner_->PostDelayedTask(
-        FROM_HERE, base::Bind(error_callback, base::Passed(&error)), {});
+        FROM_HERE, base::Bind(callback, base::Passed(&error)), {});
     return;
   }
 
   task_runner_->PostDelayedTask(
-      FROM_HERE, base::Bind(&NetworkImpl::TryToConnect,
-                            weak_ptr_factory_.GetWeakPtr(), ssid, passphrase,
-                            pid, until, success_callback, error_callback),
+      FROM_HERE,
+      base::Bind(&NetworkImpl::TryToConnect, weak_ptr_factory_.GetWeakPtr(),
+                 ssid, passphrase, pid, until, callback),
       base::TimeDelta::FromSeconds(1));
 }
 
 void NetworkImpl::Connect(const std::string& ssid,
                           const std::string& passphrase,
-                          const SuccessCallback& success_callback,
-                          const ErrorCallback& error_callback) {
+                          const DoneCallback& callback) {
   force_bootstrapping_ = false;
   CHECK(!hostapd_started_);
   if (hostapd_started_) {
     ErrorPtr error;
     Error::AddTo(&error, FROM_HERE, "wifi", "busy", "Running Access Point.");
     task_runner_->PostDelayedTask(
-        FROM_HERE, base::Bind(error_callback, base::Passed(&error)), {});
+        FROM_HERE, base::Bind(callback, base::Passed(&error)), {});
     return;
   }
 
   TryToConnect(ssid, passphrase, 0,
-               base::Time::Now() + base::TimeDelta::FromMinutes(1),
-               success_callback, error_callback);
+               base::Time::Now() + base::TimeDelta::FromMinutes(1), callback);
 }
 
 void NetworkImpl::UpdateNetworkState() {
@@ -200,23 +198,22 @@
   return std::system("nmcli dev | grep ^wlan0") == 0;
 }
 
-void NetworkImpl::OpenSslSocket(
-    const std::string& host,
-    uint16_t port,
-    const OpenSslSocketSuccessCallback& success_callback,
-    const ErrorCallback& error_callback) {
+void NetworkImpl::OpenSslSocket(const std::string& host,
+                                uint16_t port,
+                                const OpenSslSocketCallback& callback) {
   // Connect to SSL port instead of upgrading to TLS.
   std::unique_ptr<SSLStream> tls_stream{new SSLStream{task_runner_}};
 
   if (tls_stream->Init(host, port)) {
     task_runner_->PostDelayedTask(
-        FROM_HERE, base::Bind(success_callback, base::Passed(&tls_stream)), {});
+        FROM_HERE, base::Bind(callback, base::Passed(&tls_stream), nullptr),
+        {});
   } else {
     ErrorPtr error;
     Error::AddTo(&error, FROM_HERE, "tls", "tls_init_failed",
                  "Failed to initialize TLS stream.");
     task_runner_->PostDelayedTask(
-        FROM_HERE, base::Bind(error_callback, base::Passed(&error)), {});
+        FROM_HERE, base::Bind(callback, nullptr, base::Passed(&error)), {});
   }
 }
 

diff --git a/libweave/examples/ubuntu/network_manager.h b/libweave/examples/ubuntu/network_manager.h
index b8e589d..164d419 100644
--- a/libweave/examples/ubuntu/network_manager.h
+++ b/libweave/examples/ubuntu/network_manager.h

@@ -35,14 +35,12 @@
   State GetConnectionState() const override;
   void OpenSslSocket(const std::string& host,
                      uint16_t port,
-                     const OpenSslSocketSuccessCallback& success_callback,
-                     const ErrorCallback& error_callback) override;
+                     const OpenSslSocketCallback& callback) override;
 
   // Wifi implementation.
   void Connect(const std::string& ssid,
                const std::string& passphrase,
-               const SuccessCallback& success_callback,
-               const ErrorCallback& error_callback) override;
+               const DoneCallback& callback) override;
   void StartAccessPoint(const std::string& ssid) override;
   void StopAccessPoint() override;
 
@@ -53,8 +51,7 @@
                     const std::string& passphrase,
                     int pid,
                     base::Time until,
-                    const SuccessCallback& success_callback,
-                    const ErrorCallback& error_callback);
+                    const DoneCallback& callback);
   void UpdateNetworkState();
 
   bool force_bootstrapping_{false};

diff --git a/libweave/examples/ubuntu/ssl_stream.cc b/libweave/examples/ubuntu/ssl_stream.cc
index e146d58..8b17358 100644
--- a/libweave/examples/ubuntu/ssl_stream.cc
+++ b/libweave/examples/ubuntu/ssl_stream.cc

@@ -23,14 +23,13 @@
 
 void SSLStream::Read(void* buffer,
                      size_t size_to_read,
-                     const ReadSuccessCallback& success_callback,
-                     const ErrorCallback& error_callback) {
+                     const ReadCallback& callback) {
   int res = SSL_read(ssl_.get(), buffer, size_to_read);
   if (res > 0) {
     task_runner_->PostDelayedTask(
         FROM_HERE,
         base::Bind(&SSLStream::RunDelayedTask, weak_ptr_factory_.GetWeakPtr(),
-                   base::Bind(success_callback, res)),
+                   base::Bind(callback, res, nullptr)),
         {});
     return;
   }
@@ -39,9 +38,8 @@
 
   if (err == SSL_ERROR_WANT_READ || err == SSL_ERROR_WANT_WRITE) {
     task_runner_->PostDelayedTask(
-        FROM_HERE,
-        base::Bind(&SSLStream::Read, weak_ptr_factory_.GetWeakPtr(), buffer,
-                   size_to_read, success_callback, error_callback),
+        FROM_HERE, base::Bind(&SSLStream::Read, weak_ptr_factory_.GetWeakPtr(),
+                              buffer, size_to_read, callback),
         base::TimeDelta::FromSeconds(1));
     return;
   }
@@ -52,15 +50,14 @@
   task_runner_->PostDelayedTask(
       FROM_HERE,
       base::Bind(&SSLStream::RunDelayedTask, weak_ptr_factory_.GetWeakPtr(),
-                 base::Bind(error_callback, base::Passed(&weave_error))),
+                 base::Bind(callback, 0, base::Passed(&weave_error))),
       {});
   return;
 }
 
 void SSLStream::Write(const void* buffer,
                       size_t size_to_write,
-                      const SuccessCallback& success_callback,
-                      const ErrorCallback& error_callback) {
+                      const WriteCallback& callback) {
   int res = SSL_write(ssl_.get(), buffer, size_to_write);
   if (res > 0) {
     buffer = static_cast<const char*>(buffer) + res;
@@ -69,15 +66,14 @@
       task_runner_->PostDelayedTask(
           FROM_HERE,
           base::Bind(&SSLStream::RunDelayedTask, weak_ptr_factory_.GetWeakPtr(),
-                     success_callback),
+                     base::Bind(callback, nullptr)),
           {});
       return;
     }
 
     task_runner_->PostDelayedTask(
-        FROM_HERE,
-        base::Bind(&SSLStream::Write, weak_ptr_factory_.GetWeakPtr(), buffer,
-                   size_to_write, success_callback, error_callback),
+        FROM_HERE, base::Bind(&SSLStream::Write, weak_ptr_factory_.GetWeakPtr(),
+                              buffer, size_to_write, callback),
         base::TimeDelta::FromSeconds(1));
 
     return;
@@ -87,9 +83,8 @@
 
   if (err == SSL_ERROR_WANT_READ || err == SSL_ERROR_WANT_WRITE) {
     task_runner_->PostDelayedTask(
-        FROM_HERE,
-        base::Bind(&SSLStream::Write, weak_ptr_factory_.GetWeakPtr(), buffer,
-                   size_to_write, success_callback, error_callback),
+        FROM_HERE, base::Bind(&SSLStream::Write, weak_ptr_factory_.GetWeakPtr(),
+                              buffer, size_to_write, callback),
         base::TimeDelta::FromSeconds(1));
     return;
   }
@@ -100,7 +95,7 @@
   task_runner_->PostDelayedTask(
       FROM_HERE,
       base::Bind(&SSLStream::RunDelayedTask, weak_ptr_factory_.GetWeakPtr(),
-                 base::Bind(error_callback, base::Passed(&weave_error))),
+                 base::Bind(callback, base::Passed(&weave_error))),
       {});
   return;
 }

diff --git a/libweave/examples/ubuntu/ssl_stream.h b/libweave/examples/ubuntu/ssl_stream.h
index ac0d76a..859cbf9 100644
--- a/libweave/examples/ubuntu/ssl_stream.h
+++ b/libweave/examples/ubuntu/ssl_stream.h

@@ -26,13 +26,11 @@
 
   void Read(void* buffer,
             size_t size_to_read,
-            const ReadSuccessCallback& success_callback,
-            const ErrorCallback& error_callback) override;
+            const ReadCallback& callback) override;
 
   void Write(const void* buffer,
              size_t size_to_write,
-             const SuccessCallback& success_callback,
-             const ErrorCallback& error_callback) override;
+             const WriteCallback& callback) override;
 
   void CancelPendingOperations() override;
 

diff --git a/libweave/include/weave/device.h b/libweave/include/weave/device.h
index 7fbe248..09dab91 100644
--- a/libweave/include/weave/device.h
+++ b/libweave/include/weave/device.h

@@ -121,8 +121,7 @@
   // Registers the device.
   // This is testing method and should not be used by applications.
   virtual void Register(const std::string& ticket_id,
-                        const SuccessCallback& success_callback,
-                        const ErrorCallback& error_callback) = 0;
+                        const DoneCallback& callback) = 0;
 
   // Handler should display pin code to the user.
   using PairingBeginCallback =

diff --git a/libweave/include/weave/error.h b/libweave/include/weave/error.h
index 83b33b4..0869b71 100644
--- a/libweave/include/weave/error.h
+++ b/libweave/include/weave/error.h

@@ -126,8 +126,13 @@
   DISALLOW_COPY_AND_ASSIGN(Error);
 };
 
-using SuccessCallback = base::Closure;
-using ErrorCallback = base::Callback<void(ErrorPtr error)>;
+// Default callback type for async operations.
+// Function having this callback as argument should call the callback exactly
+// one time.
+// Successfully completed operation should run callback with |error| set to
+// null. Failed operation should run callback with |error| containing error
+// details.
+using DoneCallback = base::Callback<void(ErrorPtr error)>;
 
 }  // namespace weave
 

diff --git a/libweave/include/weave/provider/http_client.h b/libweave/include/weave/provider/http_client.h
index 24b4588..3c442d9 100644
--- a/libweave/include/weave/provider/http_client.h
+++ b/libweave/include/weave/provider/http_client.h

@@ -34,14 +34,14 @@
   };
 
   using Headers = std::vector<std::pair<std::string, std::string>>;
-  using SuccessCallback = base::Callback<void(const Response&)>;
+  using SendRequestCallback =
+      base::Callback<void(std::unique_ptr<Response> response, ErrorPtr error)>;
 
   virtual void SendRequest(Method method,
                            const std::string& url,
                            const Headers& headers,
                            const std::string& data,
-                           const SuccessCallback& success_callback,
-                           const ErrorCallback& error_callback) = 0;
+                           const SendRequestCallback& callback) = 0;
 
  protected:
   virtual ~HttpClient() = default;

diff --git a/libweave/include/weave/provider/network.h b/libweave/include/weave/provider/network.h
index cb3730e..4c0d5dd 100644
--- a/libweave/include/weave/provider/network.h
+++ b/libweave/include/weave/provider/network.h

@@ -29,8 +29,8 @@
   using ConnectionChangedCallback = base::Closure;
 
   // Callback type for OpenSslSocket.
-  using OpenSslSocketSuccessCallback =
-      base::Callback<void(std::unique_ptr<Stream> stream)>;
+  using OpenSslSocketCallback =
+      base::Callback<void(std::unique_ptr<Stream> stream, ErrorPtr error)>;
 
   // Subscribes to notification about changes in network connectivity. Changes
   // may include but not limited: interface up or down, new IP was assigned,
@@ -42,11 +42,9 @@
   virtual State GetConnectionState() const = 0;
 
   // Opens bidirectional sockets and returns attached stream.
-  virtual void OpenSslSocket(
-      const std::string& host,
-      uint16_t port,
-      const OpenSslSocketSuccessCallback& success_callback,
-      const ErrorCallback& error_callback) = 0;
+  virtual void OpenSslSocket(const std::string& host,
+                             uint16_t port,
+                             const OpenSslSocketCallback& callback) = 0;
 
  protected:
   virtual ~Network() = default;

diff --git a/libweave/include/weave/provider/test/mock_http_client.h b/libweave/include/weave/provider/test/mock_http_client.h
index 72cb9b8..85ac154 100644
--- a/libweave/include/weave/provider/test/mock_http_client.h
+++ b/libweave/include/weave/provider/test/mock_http_client.h

@@ -27,13 +27,12 @@
  public:
   ~MockHttpClient() override = default;
 
-  MOCK_METHOD6(SendRequest,
+  MOCK_METHOD5(SendRequest,
                void(Method,
                     const std::string&,
                     const Headers&,
                     const std::string&,
-                    const SuccessCallback&,
-                    const ErrorCallback&));
+                    const SendRequestCallback&));
 };
 
 }  // namespace test

diff --git a/libweave/include/weave/provider/test/mock_network.h b/libweave/include/weave/provider/test/mock_network.h
index e38dde2..b2811dc 100644
--- a/libweave/include/weave/provider/test/mock_network.h
+++ b/libweave/include/weave/provider/test/mock_network.h

@@ -20,11 +20,10 @@
   MOCK_METHOD1(AddConnectionChangedCallback,
                void(const ConnectionChangedCallback&));
   MOCK_CONST_METHOD0(GetConnectionState, State());
-  MOCK_METHOD4(OpenSslSocket,
+  MOCK_METHOD3(OpenSslSocket,
                void(const std::string&,
                     uint16_t,
-                    const OpenSslSocketSuccessCallback&,
-                    const ErrorCallback&));
+                    const OpenSslSocketCallback&));
 };
 
 }  // namespace test

diff --git a/libweave/include/weave/provider/test/mock_wifi.h b/libweave/include/weave/provider/test/mock_wifi.h
index 6c53d9a..5798872 100644
--- a/libweave/include/weave/provider/test/mock_wifi.h
+++ b/libweave/include/weave/provider/test/mock_wifi.h

@@ -17,11 +17,10 @@
 
 class MockWifi : public Wifi {
  public:
-  MOCK_METHOD4(Connect,
+  MOCK_METHOD3(Connect,
                void(const std::string&,
                     const std::string&,
-                    const base::Closure&,
-                    const ErrorCallback&));
+                    const DoneCallback&));
   MOCK_METHOD1(StartAccessPoint, void(const std::string&));
   MOCK_METHOD0(StopAccessPoint, void());
 };

diff --git a/libweave/include/weave/provider/wifi.h b/libweave/include/weave/provider/wifi.h
index 51f370c..aaf4609 100644
--- a/libweave/include/weave/provider/wifi.h
+++ b/libweave/include/weave/provider/wifi.h

@@ -20,8 +20,7 @@
   // should post either of callbacks.
   virtual void Connect(const std::string& ssid,
                        const std::string& passphrase,
-                       const SuccessCallback& success_callback,
-                       const ErrorCallback& error_callback) = 0;
+                       const DoneCallback& callback) = 0;
 
   // Starts WiFi access point for wifi setup.
   virtual void StartAccessPoint(const std::string& ssid) = 0;

diff --git a/libweave/include/weave/stream.h b/libweave/include/weave/stream.h
index 9d4d6fd..ea8af23 100644
--- a/libweave/include/weave/stream.h
+++ b/libweave/include/weave/stream.h

@@ -18,15 +18,14 @@
   virtual ~InputStream() = default;
 
   // Callback type for Read.
-  using ReadSuccessCallback = base::Callback<void(size_t size)>;
+  using ReadCallback = base::Callback<void(size_t size, ErrorPtr error)>;
 
-  // Implementation should return immediately and post either success_callback
-  // or error_callback. Caller guarantees that buffet is alive until either of
-  // callback is called.
+  // Implementation should return immediately and post callback after
+  // completing operation. Caller guarantees that buffet is alive until callback
+  // is called.
   virtual void Read(void* buffer,
                     size_t size_to_read,
-                    const ReadSuccessCallback& success_callback,
-                    const ErrorCallback& error_callback) = 0;
+                    const ReadCallback& callback) = 0;
 };
 
 // Interface for async input streaming.
@@ -34,14 +33,15 @@
  public:
   virtual ~OutputStream() = default;
 
-  // Implementation should return immediately and post either success_callback
-  // or error_callback. Caller guarantees that buffet is alive until either of
-  // callback is called.
+  using WriteCallback = base::Callback<void(ErrorPtr error)>;
+
+  // Implementation should return immediately and post callback after
+  // completing operation. Caller guarantees that buffet is alive until either
+  // of callback is called.
   // Success callback must be called only after all data is written.
   virtual void Write(const void* buffer,
                      size_t size_to_write,
-                     const SuccessCallback& success_callback,
-                     const ErrorCallback& error_callback) = 0;
+                     const WriteCallback& callback) = 0;
 };
 
 // Interface for async bi-directional streaming.

diff --git a/libweave/include/weave/test/fake_stream.h b/libweave/include/weave/test/fake_stream.h
index 8abb491..e5e0b57 100644
--- a/libweave/include/weave/test/fake_stream.h
+++ b/libweave/include/weave/test/fake_stream.h

@@ -31,12 +31,10 @@
   void CancelPendingOperations() override;
   void Read(void* buffer,
             size_t size_to_read,
-            const ReadSuccessCallback& success_callback,
-            const ErrorCallback& error_callback) override;
+            const ReadCallback& callback) override;
   void Write(const void* buffer,
              size_t size_to_write,
-             const SuccessCallback& success_callback,
-             const ErrorCallback& error_callback) override;
+             const WriteCallback& callback) override;
 
  private:
   provider::TaskRunner* task_runner_{nullptr};

diff --git a/libweave/include/weave/test/mock_device.h b/libweave/include/weave/test/mock_device.h
index 0d8a6da..c0a75bc 100644
--- a/libweave/include/weave/test/mock_device.h
+++ b/libweave/include/weave/test/mock_device.h

@@ -44,10 +44,9 @@
   MOCK_CONST_METHOD0(GetGcdState, GcdState());
   MOCK_METHOD1(AddGcdStateChangedCallback,
                void(const GcdStateChangedCallback& callback));
-  MOCK_METHOD3(Register,
+  MOCK_METHOD2(Register,
                void(const std::string& ticket_id,
-                    const SuccessCallback& success_callback,
-                    const ErrorCallback& error_callback));
+                    const DoneCallback& callback));
   MOCK_METHOD2(AddPairingChangedCallbacks,
                void(const PairingBeginCallback& begin_callback,
                     const PairingEndCallback& end_callback));

diff --git a/libweave/src/commands/cloud_command_proxy.cc b/libweave/src/commands/cloud_command_proxy.cc
index 3826378..41dc8ee 100644
--- a/libweave/src/commands/cloud_command_proxy.cc
+++ b/libweave/src/commands/cloud_command_proxy.cc

@@ -139,10 +139,8 @@
   command_update_in_progress_ = true;
   cloud_command_updater_->UpdateCommand(
       command_instance_->GetID(), *update_queue_.front().second,
-      base::Bind(&CloudCommandProxy::OnUpdateCommandFinished,
-                 weak_ptr_factory_.GetWeakPtr(), true),
-      base::Bind(&CloudCommandProxy::OnUpdateCommandFinished,
-                 weak_ptr_factory_.GetWeakPtr(), false));
+      base::Bind(&CloudCommandProxy::OnUpdateCommandDone,
+                 weak_ptr_factory_.GetWeakPtr()));
 }
 
 void CloudCommandProxy::ResendCommandUpdate() {
@@ -150,10 +148,10 @@
   SendCommandUpdate();
 }
 
-void CloudCommandProxy::OnUpdateCommandFinished(bool success) {
+void CloudCommandProxy::OnUpdateCommandDone(ErrorPtr error) {
   command_update_in_progress_ = false;
-  cloud_backoff_entry_->InformOfRequest(success);
-  if (success) {
+  cloud_backoff_entry_->InformOfRequest(!error);
+  if (!error) {
     // Remove the succeeded update from the queue.
     update_queue_.pop_front();
   }

diff --git a/libweave/src/commands/cloud_command_proxy.h b/libweave/src/commands/cloud_command_proxy.h
index 86dc5d3..b2ef11a 100644
--- a/libweave/src/commands/cloud_command_proxy.h
+++ b/libweave/src/commands/cloud_command_proxy.h

@@ -63,9 +63,7 @@
   void ResendCommandUpdate();
 
   // Callback invoked by the asynchronous PATCH request to the server.
-  // Called both in a case of successfully updating server command resource
-  // and in case of an error, indicated by the |success| parameter.
-  void OnUpdateCommandFinished(bool success);
+  void OnUpdateCommandDone(ErrorPtr error);
 
   // Callback invoked by the device state change queue to notify of the
   // successful device state update. |update_id| is the ID of the state that

diff --git a/libweave/src/commands/cloud_command_proxy_unittest.cc b/libweave/src/commands/cloud_command_proxy_unittest.cc
index 3c7692f..d9518e4 100644
--- a/libweave/src/commands/cloud_command_proxy_unittest.cc
+++ b/libweave/src/commands/cloud_command_proxy_unittest.cc

@@ -38,11 +38,10 @@
 
 class MockCloudCommandUpdateInterface : public CloudCommandUpdateInterface {
  public:
-  MOCK_METHOD4(UpdateCommand,
+  MOCK_METHOD3(UpdateCommand,
                void(const std::string&,
                     const base::DictionaryValue&,
-                    const base::Closure&,
-                    const base::Closure&));
+                    const DoneCallback&));
 };
 
 // Test back-off entry that uses the test clock.
@@ -147,7 +146,7 @@
 
 TEST_F(CloudCommandProxyTest, ImmediateUpdate) {
   const char expected[] = "{'state':'done'}";
-  EXPECT_CALL(cloud_updater_, UpdateCommand(kCmdID, MatchJson(expected), _, _));
+  EXPECT_CALL(cloud_updater_, UpdateCommand(kCmdID, MatchJson(expected), _));
   command_instance_->Complete({}, nullptr);
   task_runner_.RunOnce();
 }
@@ -161,7 +160,7 @@
   callbacks_.Notify(19);
   // Now we should get the update...
   const char expected[] = "{'state':'done'}";
-  EXPECT_CALL(cloud_updater_, UpdateCommand(kCmdID, MatchJson(expected), _, _));
+  EXPECT_CALL(cloud_updater_, UpdateCommand(kCmdID, MatchJson(expected), _));
   callbacks_.Notify(20);
 }
 
@@ -170,14 +169,14 @@
   //    state=inProgress
   //    progress={...}
   // The first state update is sent immediately, the second should be delayed.
-  base::Closure on_success;
+  DoneCallback callback;
   EXPECT_CALL(
       cloud_updater_,
       UpdateCommand(
           kCmdID,
-          MatchJson("{'state':'inProgress', 'progress':{'status':'ready'}}"), _,
+          MatchJson("{'state':'inProgress', 'progress':{'status':'ready'}}"),
           _))
-      .WillOnce(SaveArg<2>(&on_success));
+      .WillOnce(SaveArg<2>(&callback));
   EXPECT_TRUE(command_instance_->SetProgress(
       *CreateDictionaryValue("{'status': 'ready'}"), nullptr));
 
@@ -200,34 +199,35 @@
     'progress': {'status':'ready'},
     'state':'inProgress'
   })";
-  EXPECT_CALL(cloud_updater_, UpdateCommand(kCmdID, MatchJson(expected), _, _));
+  EXPECT_CALL(cloud_updater_, UpdateCommand(kCmdID, MatchJson(expected), _));
   callbacks_.Notify(20);
 }
 
 TEST_F(CloudCommandProxyTest, RetryFailed) {
-  base::Closure on_success;
-  base::Closure on_error;
+  DoneCallback callback;
 
   const char expect[] =
       "{'state':'inProgress', 'progress': {'status': 'ready'}}";
-  EXPECT_CALL(cloud_updater_, UpdateCommand(kCmdID, MatchJson(expect), _, _))
+  EXPECT_CALL(cloud_updater_, UpdateCommand(kCmdID, MatchJson(expect), _))
       .Times(3)
-      .WillRepeatedly(DoAll(SaveArg<2>(&on_success), SaveArg<3>(&on_error)));
+      .WillRepeatedly(SaveArg<2>(&callback));
   auto started = task_runner_.GetClock()->Now();
   EXPECT_TRUE(command_instance_->SetProgress(
       *CreateDictionaryValue("{'status': 'ready'}"), nullptr));
   task_runner_.Run();
-  on_error.Run();
+  ErrorPtr error;
+  Error::AddTo(&error, FROM_HERE, "TEST", "TEST", "TEST");
+  callback.Run(error->Clone());
   task_runner_.Run();
   EXPECT_GE(task_runner_.GetClock()->Now() - started,
             base::TimeDelta::FromSecondsD(0.9));
 
-  on_error.Run();
+  callback.Run(error->Clone());
   task_runner_.Run();
   EXPECT_GE(task_runner_.GetClock()->Now() - started,
             base::TimeDelta::FromSecondsD(2.9));
 
-  on_success.Run();
+  callback.Run(nullptr);
   task_runner_.Run();
   EXPECT_GE(task_runner_.GetClock()->Now() - started,
             base::TimeDelta::FromSecondsD(2.9));
@@ -244,20 +244,20 @@
   command_instance_->Complete({}, nullptr);
 
   // Device state #20 updated.
-  base::Closure on_success;
+  DoneCallback callback;
   const char expect1[] = R"({
     'progress': {'status':'ready'},
     'state':'inProgress'
   })";
-  EXPECT_CALL(cloud_updater_, UpdateCommand(kCmdID, MatchJson(expect1), _, _))
-      .WillOnce(SaveArg<2>(&on_success));
+  EXPECT_CALL(cloud_updater_, UpdateCommand(kCmdID, MatchJson(expect1), _))
+      .WillOnce(SaveArg<2>(&callback));
   callbacks_.Notify(20);
-  on_success.Run();
+  callback.Run(nullptr);
 
   // Device state #21 updated.
   const char expect2[] = "{'progress': {'status':'busy'}}";
-  EXPECT_CALL(cloud_updater_, UpdateCommand(kCmdID, MatchJson(expect2), _, _))
-      .WillOnce(SaveArg<2>(&on_success));
+  EXPECT_CALL(cloud_updater_, UpdateCommand(kCmdID, MatchJson(expect2), _))
+      .WillOnce(SaveArg<2>(&callback));
   callbacks_.Notify(21);
 
   // Device state #22 updated. Nothing happens here since the previous command
@@ -267,9 +267,9 @@
   // Now the command update is complete, send out the patch that happened after
   // the state #22 was updated.
   const char expect3[] = "{'state': 'done'}";
-  EXPECT_CALL(cloud_updater_, UpdateCommand(kCmdID, MatchJson(expect3), _, _))
-      .WillOnce(SaveArg<2>(&on_success));
-  on_success.Run();
+  EXPECT_CALL(cloud_updater_, UpdateCommand(kCmdID, MatchJson(expect3), _))
+      .WillOnce(SaveArg<2>(&callback));
+  callback.Run(nullptr);
 }
 
 TEST_F(CloudCommandProxyTest, CombineSomeStates) {
@@ -283,22 +283,22 @@
   command_instance_->Complete({}, nullptr);
 
   // Device state 20-21 updated.
-  base::Closure on_success;
+  DoneCallback callback;
   const char expect1[] = R"({
     'progress': {'status':'busy'},
     'state':'inProgress'
   })";
-  EXPECT_CALL(cloud_updater_, UpdateCommand(kCmdID, MatchJson(expect1), _, _))
-      .WillOnce(SaveArg<2>(&on_success));
+  EXPECT_CALL(cloud_updater_, UpdateCommand(kCmdID, MatchJson(expect1), _))
+      .WillOnce(SaveArg<2>(&callback));
   callbacks_.Notify(21);
-  on_success.Run();
+  callback.Run(nullptr);
 
   // Device state #22 updated.
   const char expect2[] = "{'state': 'done'}";
-  EXPECT_CALL(cloud_updater_, UpdateCommand(kCmdID, MatchJson(expect2), _, _))
-      .WillOnce(SaveArg<2>(&on_success));
+  EXPECT_CALL(cloud_updater_, UpdateCommand(kCmdID, MatchJson(expect2), _))
+      .WillOnce(SaveArg<2>(&callback));
   callbacks_.Notify(22);
-  on_success.Run();
+  callback.Run(nullptr);
 }
 
 TEST_F(CloudCommandProxyTest, CombineAllStates) {
@@ -316,7 +316,7 @@
     'progress': {'status':'busy'},
     'state':'done'
   })";
-  EXPECT_CALL(cloud_updater_, UpdateCommand(kCmdID, MatchJson(expected), _, _));
+  EXPECT_CALL(cloud_updater_, UpdateCommand(kCmdID, MatchJson(expected), _));
   callbacks_.Notify(30);
 }
 
@@ -336,7 +336,7 @@
     'results': {'sum':30},
     'state':'done'
   })";
-  EXPECT_CALL(cloud_updater_, UpdateCommand(kCmdID, MatchJson(expected), _, _));
+  EXPECT_CALL(cloud_updater_, UpdateCommand(kCmdID, MatchJson(expected), _));
   callbacks_.Notify(30);
 }
 
@@ -352,7 +352,7 @@
 
   // As soon as we change the command, the update to the server should be sent.
   const char expected[] = "{'state':'done'}";
-  EXPECT_CALL(cloud_updater_, UpdateCommand(kCmdID, MatchJson(expected), _, _));
+  EXPECT_CALL(cloud_updater_, UpdateCommand(kCmdID, MatchJson(expected), _));
   command_instance_->Complete({}, nullptr);
   task_runner_.RunOnce();
 }
@@ -370,7 +370,7 @@
 
   // Only when the state #20 is published we should update the command
   const char expected[] = "{'state':'done'}";
-  EXPECT_CALL(cloud_updater_, UpdateCommand(kCmdID, MatchJson(expected), _, _));
+  EXPECT_CALL(cloud_updater_, UpdateCommand(kCmdID, MatchJson(expected), _));
   callbacks_.Notify(20);
 }
 

diff --git a/libweave/src/commands/cloud_command_update_interface.h b/libweave/src/commands/cloud_command_update_interface.h
index 5bd5c11..71c2f18 100644
--- a/libweave/src/commands/cloud_command_update_interface.h
+++ b/libweave/src/commands/cloud_command_update_interface.h

@@ -18,8 +18,7 @@
  public:
   virtual void UpdateCommand(const std::string& command_id,
                              const base::DictionaryValue& command_patch,
-                             const base::Closure& on_success,
-                             const base::Closure& on_error) = 0;
+                             const DoneCallback& callback) = 0;
 
  protected:
   virtual ~CloudCommandUpdateInterface() = default;

diff --git a/libweave/src/device_manager.cc b/libweave/src/device_manager.cc
index 9105352..54570f6 100644
--- a/libweave/src/device_manager.cc
+++ b/libweave/src/device_manager.cc

@@ -152,9 +152,8 @@
 }
 
 void DeviceManager::Register(const std::string& ticket_id,
-                             const SuccessCallback& success_callback,
-                             const ErrorCallback& error_callback) {
-  device_info_->RegisterDevice(ticket_id, success_callback, error_callback);
+                             const DoneCallback& callback) {
+  device_info_->RegisterDevice(ticket_id, callback);
 }
 
 void DeviceManager::AddPairingChangedCallbacks(

diff --git a/libweave/src/device_manager.h b/libweave/src/device_manager.h
index 16e0601..7bded15 100644
--- a/libweave/src/device_manager.h
+++ b/libweave/src/device_manager.h

@@ -59,8 +59,7 @@
                         ErrorPtr* error) override;
   std::unique_ptr<base::DictionaryValue> GetState() const override;
   void Register(const std::string& ticket_id,
-                const SuccessCallback& success_callback,
-                const ErrorCallback& error_callback) override;
+                const DoneCallback& callback) override;
   GcdState GetGcdState() const override;
   void AddGcdStateChangedCallback(
       const GcdStateChangedCallback& callback) override;

diff --git a/libweave/src/device_registration_info.cc b/libweave/src/device_registration_info.cc
index 6481481..e35b768 100644
--- a/libweave/src/device_registration_info.cc
+++ b/libweave/src/device_registration_info.cc

@@ -98,17 +98,18 @@
   return AppendQueryParams(result, params);
 }
 
-void IgnoreCloudError(ErrorPtr) {}
-
 void IgnoreCloudErrorWithCallback(const base::Closure& cb, ErrorPtr) {
   cb.Run();
 }
 
-void IgnoreCloudResult(const base::DictionaryValue&) {}
+void IgnoreCloudError(ErrorPtr) {}
 
-void IgnoreCloudResultWithCallback(const base::Closure& cb,
-                                   const base::DictionaryValue&) {
-  cb.Run();
+void IgnoreCloudResult(const base::DictionaryValue&, ErrorPtr error) {}
+
+void IgnoreCloudResultWithCallback(const DoneCallback& cb,
+                                   const base::DictionaryValue&,
+                                   ErrorPtr error) {
+  cb.Run(std::move(error));
 }
 
 class RequestSender final {
@@ -118,31 +119,28 @@
                 HttpClient* transport)
       : method_{method}, url_{url}, transport_{transport} {}
 
-  void Send(const HttpClient::SuccessCallback& success_callback,
-            const ErrorCallback& error_callback) {
+  void Send(const HttpClient::SendRequestCallback& callback) {
     static int debug_id = 0;
     ++debug_id;
     VLOG(1) << "Sending request. id:" << debug_id
             << " method:" << EnumToString(method_) << " url:" << url_;
     VLOG(2) << "Request data: " << data_;
-    auto on_success = [](int debug_id,
-                         const HttpClient::SuccessCallback& success_callback,
-                         const HttpClient::Response& response) {
-      VLOG(1) << "Request succeeded. id:" << debug_id << " status:" <<
-      response.GetStatusCode();
-      VLOG(2) << "Response data: " << response.GetData();
-      success_callback.Run(response);
-    };
-    auto on_error = [](int debug_id, const ErrorCallback& error_callback,
-                       ErrorPtr error) {
-      VLOG(1) << "Request failed, id=" << debug_id
-              << ", reason: " << error->GetCode()
-              << ", message: " << error->GetMessage();
-      error_callback.Run(std::move(error));
+    auto on_done = [](
+        int debug_id, const HttpClient::SendRequestCallback& callback,
+        std::unique_ptr<HttpClient::Response> response, ErrorPtr error) {
+      if (error) {
+        VLOG(1) << "Request failed, id=" << debug_id
+                << ", reason: " << error->GetCode()
+                << ", message: " << error->GetMessage();
+        return callback.Run({}, std::move(error));
+      }
+      VLOG(1) << "Request succeeded. id:" << debug_id
+              << " status:" << response->GetStatusCode();
+      VLOG(2) << "Response data: " << response->GetData();
+      callback.Run(std::move(response), nullptr);
     };
     transport_->SendRequest(method_, url_, GetFullHeaders(), data_,
-                            base::Bind(on_success, debug_id, success_callback),
-                            base::Bind(on_error, debug_id, error_callback));
+                            base::Bind(on_done, debug_id, callback));
   }
 
   void SetAccessToken(const std::string& access_token) {
@@ -304,7 +302,8 @@
     return;  // Assume we're in test
   task_runner_->PostDelayedTask(
       FROM_HERE,
-      base::Bind(&DeviceRegistrationInfo::ConnectToCloud, AsWeakPtr()), delay);
+      base::Bind(&DeviceRegistrationInfo::ConnectToCloud, AsWeakPtr(), nullptr),
+      delay);
 }
 
 bool DeviceRegistrationInfo::HaveRegistrationCredentials() const {
@@ -350,16 +349,12 @@
   return resp;
 }
 
-void DeviceRegistrationInfo::RefreshAccessToken(
-    const base::Closure& success_callback,
-    const ErrorCallback& error_callback) {
+void DeviceRegistrationInfo::RefreshAccessToken(const DoneCallback& callback) {
   LOG(INFO) << "Refreshing access token.";
 
   ErrorPtr error;
-  if (!VerifyRegistrationCredentials(&error)) {
-    error_callback.Run(std::move(error));
-    return;
-  }
+  if (!VerifyRegistrationCredentials(&error))
+    return callback.Run(std::move(error));
 
   if (oauth2_backoff_entry_->ShouldRejectRequest()) {
     VLOG(1) << "RefreshToken request delayed for "
@@ -367,19 +362,11 @@
             << " due to backoff policy";
     task_runner_->PostDelayedTask(
         FROM_HERE, base::Bind(&DeviceRegistrationInfo::RefreshAccessToken,
-                              AsWeakPtr(), success_callback, error_callback),
+                              AsWeakPtr(), callback),
         oauth2_backoff_entry_->GetTimeUntilRelease());
     return;
   }
 
-  // Make a shared pointer to |success_callback| and |error_callback| since we
-  // are going to share these callbacks with both success and error callbacks
-  // for PostFormData() and if the callbacks have any move-only types,
-  // one of the copies will be bad.
-  auto shared_success_callback =
-      std::make_shared<base::Closure>(success_callback);
-  auto shared_error_callback = std::make_shared<ErrorCallback>(error_callback);
-
   RequestSender sender{HttpClient::Method::kPost, GetOAuthURL("token"),
                        http_client_};
   sender.SetFormData({
@@ -388,25 +375,25 @@
       {"client_secret", GetSettings().client_secret},
       {"grant_type", "refresh_token"},
   });
-  sender.Send(base::Bind(&DeviceRegistrationInfo::OnRefreshAccessTokenSuccess,
-                         weak_factory_.GetWeakPtr(), shared_success_callback,
-                         shared_error_callback),
-              base::Bind(&DeviceRegistrationInfo::OnRefreshAccessTokenError,
-                         weak_factory_.GetWeakPtr(), shared_success_callback,
-                         shared_error_callback));
+  sender.Send(base::Bind(&DeviceRegistrationInfo::OnRefreshAccessTokenDone,
+                         weak_factory_.GetWeakPtr(), callback));
   VLOG(1) << "Refresh access token request dispatched";
 }
 
-void DeviceRegistrationInfo::OnRefreshAccessTokenSuccess(
-    const std::shared_ptr<base::Closure>& success_callback,
-    const std::shared_ptr<ErrorCallback>& error_callback,
-    const HttpClient::Response& response) {
+void DeviceRegistrationInfo::OnRefreshAccessTokenDone(
+    const DoneCallback& callback,
+    std::unique_ptr<HttpClient::Response> response,
+    ErrorPtr error) {
+  if (error) {
+    VLOG(1) << "Refresh access token failed";
+    oauth2_backoff_entry_->InformOfRequest(false);
+    return RefreshAccessToken(callback);
+  }
   VLOG(1) << "Refresh access token request completed";
   oauth2_backoff_entry_->InformOfRequest(true);
-  ErrorPtr error;
-  auto json = ParseOAuthResponse(response, &error);
+  auto json = ParseOAuthResponse(*response, &error);
   if (!json)
-    return error_callback->Run(std::move(error));
+    return callback.Run(std::move(error));
 
   int expires_in = 0;
   if (!json->GetString("access_token", &access_token_) ||
@@ -415,7 +402,7 @@
     LOG(ERROR) << "Access token unavailable.";
     Error::AddTo(&error, FROM_HERE, kErrorDomainOAuth2,
                  "unexpected_server_response", "Access token unavailable");
-    return error_callback->Run(std::move(error));
+    return callback.Run(std::move(error));
   }
   access_token_expiration_ =
       base::Time::Now() + base::TimeDelta::FromSeconds(expires_in);
@@ -428,16 +415,7 @@
     // Now that we have a new access token, retry the connection.
     StartNotificationChannel();
   }
-  success_callback->Run();
-}
-
-void DeviceRegistrationInfo::OnRefreshAccessTokenError(
-    const std::shared_ptr<base::Closure>& success_callback,
-    const std::shared_ptr<ErrorCallback>& error_callback,
-    ErrorPtr error) {
-  VLOG(1) << "Refresh access token failed";
-  oauth2_backoff_entry_->InformOfRequest(false);
-  RefreshAccessToken(*success_callback, *error_callback);
+  callback.Run(nullptr);
 }
 
 void DeviceRegistrationInfo::StartNotificationChannel() {
@@ -522,45 +500,27 @@
 }
 
 void DeviceRegistrationInfo::GetDeviceInfo(
-    const CloudRequestCallback& success_callback,
-    const ErrorCallback& error_callback) {
+    const CloudRequestDoneCallback& callback) {
   ErrorPtr error;
   if (!VerifyRegistrationCredentials(&error)) {
-    if (!error_callback.is_null())
-      error_callback.Run(std::move(error));
-    return;
+    return callback.Run({}, std::move(error));
   }
-  DoCloudRequest(HttpClient::Method::kGet, GetDeviceURL(), nullptr,
-                 success_callback, error_callback);
+  DoCloudRequest(HttpClient::Method::kGet, GetDeviceURL(), nullptr, callback);
 }
 
-struct DeviceRegistrationInfo::RegisterCallbacks {
-  RegisterCallbacks(const SuccessCallback& success, const ErrorCallback& error)
-      : success_callback{success}, error_callback{error} {}
-  SuccessCallback success_callback;
-  ErrorCallback error_callback;
-};
-
-void DeviceRegistrationInfo::RegisterDeviceError(
-    const std::shared_ptr<RegisterCallbacks>& callbacks,
-    ErrorPtr error) {
-  task_runner_->PostDelayedTask(
-      FROM_HERE, base::Bind(callbacks->error_callback, base::Passed(&error)),
-      {});
+void DeviceRegistrationInfo::RegisterDeviceError(const DoneCallback& callback,
+                                                 ErrorPtr error) {
+  task_runner_->PostDelayedTask(FROM_HERE,
+                                base::Bind(callback, base::Passed(&error)), {});
 }
 
-void DeviceRegistrationInfo::RegisterDevice(
-    const std::string& ticket_id,
-    const SuccessCallback& success_callback,
-    const ErrorCallback& error_callback) {
-  auto callbacks =
-      std::make_shared<RegisterCallbacks>(success_callback, error_callback);
-
+void DeviceRegistrationInfo::RegisterDevice(const std::string& ticket_id,
+                                            const DoneCallback& callback) {
   ErrorPtr error;
   std::unique_ptr<base::DictionaryValue> device_draft =
       BuildDeviceResource(&error);
   if (!device_draft)
-    return RegisterDeviceError(callbacks, std::move(error));
+    return RegisterDeviceError(callback, std::move(error));
 
   base::DictionaryValue req_json;
   req_json.SetString("id", ticket_id);
@@ -573,23 +533,23 @@
   RequestSender sender{HttpClient::Method::kPatch, url, http_client_};
   sender.SetJsonData(req_json);
   sender.Send(base::Bind(&DeviceRegistrationInfo::RegisterDeviceOnTicketSent,
-                         weak_factory_.GetWeakPtr(), ticket_id, callbacks),
-              base::Bind(&DeviceRegistrationInfo::RegisterDeviceError,
-                         weak_factory_.GetWeakPtr(), callbacks));
+                         weak_factory_.GetWeakPtr(), ticket_id, callback));
 }
 
 void DeviceRegistrationInfo::RegisterDeviceOnTicketSent(
     const std::string& ticket_id,
-    const std::shared_ptr<RegisterCallbacks>& callbacks,
-    const provider::HttpClient::Response& response) {
-  ErrorPtr error;
-  auto json_resp = ParseJsonResponse(response, &error);
+    const DoneCallback& callback,
+    std::unique_ptr<provider::HttpClient::Response> response,
+    ErrorPtr error) {
+  if (error)
+    return RegisterDeviceError(callback, std::move(error));
+  auto json_resp = ParseJsonResponse(*response, &error);
   if (!json_resp)
-    return RegisterDeviceError(callbacks, std::move(error));
+    return RegisterDeviceError(callback, std::move(error));
 
-  if (!IsSuccessful(response)) {
+  if (!IsSuccessful(*response)) {
     ParseGCDError(json_resp.get(), &error);
-    return RegisterDeviceError(callbacks, std::move(error));
+    return RegisterDeviceError(callback, std::move(error));
   }
 
   std::string url =
@@ -597,21 +557,21 @@
                     {{"key", GetSettings().api_key}});
   RequestSender{HttpClient::Method::kPost, url, http_client_}.Send(
       base::Bind(&DeviceRegistrationInfo::RegisterDeviceOnTicketFinalized,
-                 weak_factory_.GetWeakPtr(), callbacks),
-      base::Bind(&DeviceRegistrationInfo::RegisterDeviceError,
-                 weak_factory_.GetWeakPtr(), callbacks));
+                 weak_factory_.GetWeakPtr(), callback));
 }
 
 void DeviceRegistrationInfo::RegisterDeviceOnTicketFinalized(
-    const std::shared_ptr<RegisterCallbacks>& callbacks,
-    const provider::HttpClient::Response& response) {
-  ErrorPtr error;
-  auto json_resp = ParseJsonResponse(response, &error);
+    const DoneCallback& callback,
+    std::unique_ptr<provider::HttpClient::Response> response,
+    ErrorPtr error) {
+  if (error)
+    return RegisterDeviceError(callback, std::move(error));
+  auto json_resp = ParseJsonResponse(*response, &error);
   if (!json_resp)
-    return RegisterDeviceError(callbacks, std::move(error));
-  if (!IsSuccessful(response)) {
+    return RegisterDeviceError(callback, std::move(error));
+  if (!IsSuccessful(*response)) {
     ParseGCDError(json_resp.get(), &error);
-    return RegisterDeviceError(callbacks, std::move(error));
+    return RegisterDeviceError(callback, std::move(error));
   }
 
   std::string auth_code;
@@ -624,7 +584,7 @@
       !device_draft_response->GetString("id", &cloud_id)) {
     Error::AddTo(&error, FROM_HERE, kErrorDomainGCD, "unexpected_response",
                  "Device account missing in response");
-    return RegisterDeviceError(callbacks, std::move(error));
+    return RegisterDeviceError(callback, std::move(error));
   }
 
   UpdateDeviceInfoTimestamp(*device_draft_response);
@@ -641,18 +601,18 @@
        {"grant_type", "authorization_code"}});
   sender2.Send(base::Bind(&DeviceRegistrationInfo::RegisterDeviceOnAuthCodeSent,
                           weak_factory_.GetWeakPtr(), cloud_id, robot_account,
-                          callbacks),
-               base::Bind(&DeviceRegistrationInfo::RegisterDeviceError,
-                          weak_factory_.GetWeakPtr(), callbacks));
+                          callback));
 }
 
 void DeviceRegistrationInfo::RegisterDeviceOnAuthCodeSent(
     const std::string& cloud_id,
     const std::string& robot_account,
-    const std::shared_ptr<RegisterCallbacks>& callbacks,
-    const provider::HttpClient::Response& response) {
-  ErrorPtr error;
-  auto json_resp = ParseOAuthResponse(response, &error);
+    const DoneCallback& callback,
+    std::unique_ptr<provider::HttpClient::Response> response,
+    ErrorPtr error) {
+  if (error)
+    return RegisterDeviceError(callback, std::move(error));
+  auto json_resp = ParseOAuthResponse(*response, &error);
   int expires_in = 0;
   std::string refresh_token;
   if (!json_resp || !json_resp->GetString("access_token", &access_token_) ||
@@ -661,7 +621,7 @@
       access_token_.empty() || refresh_token.empty() || expires_in <= 0) {
     Error::AddTo(&error, FROM_HERE, kErrorDomainGCD, "unexpected_response",
                  "Device access_token missing in response");
-    return RegisterDeviceError(callbacks, std::move(error));
+    return RegisterDeviceError(callback, std::move(error));
   }
 
   access_token_expiration_ =
@@ -673,7 +633,7 @@
   change.set_refresh_token(refresh_token);
   change.Commit();
 
-  task_runner_->PostDelayedTask(FROM_HERE, callbacks->success_callback, {});
+  task_runner_->PostDelayedTask(FROM_HERE, base::Bind(callback, nullptr), {});
 
   StartNotificationChannel();
 
@@ -686,10 +646,9 @@
     HttpClient::Method method,
     const std::string& url,
     const base::DictionaryValue* body,
-    const CloudRequestCallback& success_callback,
-    const ErrorCallback& error_callback) {
+    const CloudRequestDoneCallback& callback) {
   // We make CloudRequestData shared here because we want to make sure
-  // there is only one instance of success_callback and error_calback since
+  // there is only one instance of callback and error_calback since
   // those may have move-only types and making a copy of the callback with
   // move-only types curried-in will invalidate the source callback.
   auto data = std::make_shared<CloudRequestData>();
@@ -697,8 +656,7 @@
   data->url = url;
   if (body)
     base::JSONWriter::Write(*body, &data->body);
-  data->success_callback = success_callback;
-  data->error_callback = error_callback;
+  data->callback = callback;
   SendCloudRequest(data);
 }
 
@@ -710,7 +668,7 @@
 
   ErrorPtr error;
   if (!VerifyRegistrationCredentials(&error)) {
-    return data->error_callback.Run(std::move(error));
+    return data->callback.Run({}, std::move(error));
   }
 
   if (cloud_backoff_entry_->ShouldRejectRequest()) {
@@ -726,22 +684,21 @@
   RequestSender sender{data->method, data->url, http_client_};
   sender.SetData(data->body, http::kJsonUtf8);
   sender.SetAccessToken(access_token_);
-  sender.Send(base::Bind(&DeviceRegistrationInfo::OnCloudRequestSuccess,
-                         AsWeakPtr(), data),
-              base::Bind(&DeviceRegistrationInfo::OnCloudRequestError,
+  sender.Send(base::Bind(&DeviceRegistrationInfo::OnCloudRequestDone,
                          AsWeakPtr(), data));
 }
 
-void DeviceRegistrationInfo::OnCloudRequestSuccess(
+void DeviceRegistrationInfo::OnCloudRequestDone(
     const std::shared_ptr<const CloudRequestData>& data,
-    const HttpClient::Response& response) {
-  int status_code = response.GetStatusCode();
+    std::unique_ptr<provider::HttpClient::Response> response,
+    ErrorPtr error) {
+  if (error)
+    return RetryCloudRequest(data);
+  int status_code = response->GetStatusCode();
   if (status_code == http::kDenied) {
     cloud_backoff_entry_->InformOfRequest(true);
     RefreshAccessToken(
         base::Bind(&DeviceRegistrationInfo::OnAccessTokenRefreshed, AsWeakPtr(),
-                   data),
-        base::Bind(&DeviceRegistrationInfo::OnAccessTokenError, AsWeakPtr(),
                    data));
     return;
   }
@@ -755,14 +712,13 @@
     return;
   }
 
-  ErrorPtr error;
-  auto json_resp = ParseJsonResponse(response, &error);
+  auto json_resp = ParseJsonResponse(*response, &error);
   if (!json_resp) {
     cloud_backoff_entry_->InformOfRequest(true);
-    return data->error_callback.Run(std::move(error));
+    return data->callback.Run({}, std::move(error));
   }
 
-  if (!IsSuccessful(response)) {
+  if (!IsSuccessful(*response)) {
     ParseGCDError(json_resp.get(), &error);
     if (status_code == http::kForbidden &&
         error->HasError(kErrorDomainGCDServer, "rateLimitExceeded")) {
@@ -770,18 +726,12 @@
       return RetryCloudRequest(data);
     }
     cloud_backoff_entry_->InformOfRequest(true);
-    return data->error_callback.Run(std::move(error));
+    return data->callback.Run({}, std::move(error));
   }
 
   cloud_backoff_entry_->InformOfRequest(true);
   SetGcdState(GcdState::kConnected);
-  data->success_callback.Run(*json_resp);
-}
-
-void DeviceRegistrationInfo::OnCloudRequestError(
-    const std::shared_ptr<const CloudRequestData>& data,
-    ErrorPtr error) {
-  RetryCloudRequest(data);
+  data->callback.Run(*json_resp, nullptr);
 }
 
 void DeviceRegistrationInfo::RetryCloudRequest(
@@ -793,32 +743,34 @@
 }
 
 void DeviceRegistrationInfo::OnAccessTokenRefreshed(
-    const std::shared_ptr<const CloudRequestData>& data) {
+    const std::shared_ptr<const CloudRequestData>& data,
+    ErrorPtr error) {
+  if (error) {
+    CheckAccessTokenError(error->Clone());
+    return data->callback.Run({}, std::move(error));
+  }
   SendCloudRequest(data);
 }
 
-void DeviceRegistrationInfo::OnAccessTokenError(
-    const std::shared_ptr<const CloudRequestData>& data,
-    ErrorPtr error) {
-  CheckAccessTokenError(error->Clone());
-  data->error_callback.Run(std::move(error));
-}
-
 void DeviceRegistrationInfo::CheckAccessTokenError(ErrorPtr error) {
-  if (error->HasError(kErrorDomainOAuth2, "invalid_grant"))
+  if (error && error->HasError(kErrorDomainOAuth2, "invalid_grant"))
     MarkDeviceUnregistered();
 }
 
-void DeviceRegistrationInfo::ConnectToCloud() {
+void DeviceRegistrationInfo::ConnectToCloud(ErrorPtr error) {
+  if (error) {
+    if (error->HasError(kErrorDomainOAuth2, "invalid_grant"))
+      MarkDeviceUnregistered();
+    return;
+  }
+
   connected_to_cloud_ = false;
   if (!VerifyRegistrationCredentials(nullptr))
     return;
 
   if (access_token_.empty()) {
     RefreshAccessToken(
-        base::Bind(&DeviceRegistrationInfo::ConnectToCloud, AsWeakPtr()),
-        base::Bind(&DeviceRegistrationInfo::CheckAccessTokenError,
-                   AsWeakPtr()));
+        base::Bind(&DeviceRegistrationInfo::ConnectToCloud, AsWeakPtr()));
     return;
   }
 
@@ -828,16 +780,16 @@
   //   3) abort any commands that we've previously marked as "in progress"
   //      or as being in an error state; publish queued commands
   UpdateDeviceResource(
-      base::Bind(&DeviceRegistrationInfo::OnConnectedToCloud, AsWeakPtr()),
-      base::Bind(&IgnoreCloudError));
+      base::Bind(&DeviceRegistrationInfo::OnConnectedToCloud, AsWeakPtr()));
 }
 
-void DeviceRegistrationInfo::OnConnectedToCloud() {
+void DeviceRegistrationInfo::OnConnectedToCloud(ErrorPtr error) {
+  if (error)
+    return;
   LOG(INFO) << "Device connected to cloud server";
   connected_to_cloud_ = true;
   FetchCommands(base::Bind(&DeviceRegistrationInfo::ProcessInitialCommandList,
-                           AsWeakPtr()),
-                base::Bind(&IgnoreCloudError));
+                           AsWeakPtr()));
   // In case there are any pending state updates since we sent off the initial
   // UpdateDeviceResource() request, update the server with any state changes.
   PublishStateUpdates();
@@ -853,8 +805,7 @@
   change.Commit();
 
   if (HaveRegistrationCredentials()) {
-    UpdateDeviceResource(base::Bind(&base::DoNothing),
-                         base::Bind(&IgnoreCloudError));
+    UpdateDeviceResource(base::Bind(&IgnoreCloudError));
   }
 }
 
@@ -891,12 +842,10 @@
 void DeviceRegistrationInfo::UpdateCommand(
     const std::string& command_id,
     const base::DictionaryValue& command_patch,
-    const base::Closure& on_success,
-    const base::Closure& on_error) {
+    const DoneCallback& callback) {
   DoCloudRequest(HttpClient::Method::kPatch,
                  GetServiceURL("commands/" + command_id), &command_patch,
-                 base::Bind(&IgnoreCloudResultWithCallback, on_success),
-                 base::Bind(&IgnoreCloudErrorWithCallback, on_error));
+                 base::Bind(&IgnoreCloudResultWithCallback, callback));
 }
 
 void DeviceRegistrationInfo::NotifyCommandAborted(const std::string& command_id,
@@ -908,14 +857,12 @@
     command_patch.Set(commands::attributes::kCommand_Error,
                       ErrorInfoToJson(*error).release());
   }
-  UpdateCommand(command_id, command_patch, base::Bind(&base::DoNothing),
-                base::Bind(&base::DoNothing));
+  UpdateCommand(command_id, command_patch, base::Bind(&IgnoreCloudError));
 }
 
 void DeviceRegistrationInfo::UpdateDeviceResource(
-    const base::Closure& on_success,
-    const ErrorCallback& on_failure) {
-  queued_resource_update_callbacks_.emplace_back(on_success, on_failure);
+    const DoneCallback& callback) {
+  queued_resource_update_callbacks_.emplace_back(callback);
   if (!in_progress_resource_update_callbacks_.empty()) {
     VLOG(1) << "Another request is already pending.";
     return;
@@ -935,10 +882,8 @@
     // the request to guard against out-of-order requests overwriting settings
     // specified by later requests.
     VLOG(1) << "Getting the last device resource timestamp from server...";
-    GetDeviceInfo(
-        base::Bind(&DeviceRegistrationInfo::OnDeviceInfoRetrieved, AsWeakPtr()),
-        base::Bind(&DeviceRegistrationInfo::OnUpdateDeviceResourceError,
-                   AsWeakPtr()));
+    GetDeviceInfo(base::Bind(&DeviceRegistrationInfo::OnDeviceInfoRetrieved,
+                             AsWeakPtr()));
     return;
   }
 
@@ -959,16 +904,16 @@
   std::string url = GetDeviceURL(
       {}, {{"lastUpdateTimeMs", last_device_resource_updated_timestamp_}});
 
-  DoCloudRequest(
-      HttpClient::Method::kPut, url, device_resource.get(),
-      base::Bind(&DeviceRegistrationInfo::OnUpdateDeviceResourceSuccess,
-                 AsWeakPtr()),
-      base::Bind(&DeviceRegistrationInfo::OnUpdateDeviceResourceError,
-                 AsWeakPtr()));
+  DoCloudRequest(HttpClient::Method::kPut, url, device_resource.get(),
+                 base::Bind(&DeviceRegistrationInfo::OnUpdateDeviceResourceDone,
+                            AsWeakPtr()));
 }
 
 void DeviceRegistrationInfo::OnDeviceInfoRetrieved(
-    const base::DictionaryValue& device_info) {
+    const base::DictionaryValue& device_info,
+    ErrorPtr error) {
+  if (error)
+    return OnUpdateDeviceResourceError(std::move(error));
   if (UpdateDeviceInfoTimestamp(device_info))
     StartQueuedUpdateDeviceResource();
 }
@@ -987,15 +932,18 @@
   return true;
 }
 
-void DeviceRegistrationInfo::OnUpdateDeviceResourceSuccess(
-    const base::DictionaryValue& device_info) {
+void DeviceRegistrationInfo::OnUpdateDeviceResourceDone(
+    const base::DictionaryValue& device_info,
+    ErrorPtr error) {
+  if (error)
+    return OnUpdateDeviceResourceError(std::move(error));
   UpdateDeviceInfoTimestamp(device_info);
   // Make a copy of the callback list so that if the callback triggers another
   // call to UpdateDeviceResource(), we do not modify the list we are iterating
   // over.
   auto callback_list = std::move(in_progress_resource_update_callbacks_);
-  for (const auto& callback_pair : callback_list)
-    callback_pair.first.Run();
+  for (const auto& callback : callback_list)
+    callback.Run(nullptr);
   StartQueuedUpdateDeviceResource();
 }
 
@@ -1004,10 +952,8 @@
     // If the server rejected our previous request, retrieve the latest
     // timestamp from the server and retry.
     VLOG(1) << "Getting the last device resource timestamp from server...";
-    GetDeviceInfo(
-        base::Bind(&DeviceRegistrationInfo::OnDeviceInfoRetrieved, AsWeakPtr()),
-        base::Bind(&DeviceRegistrationInfo::OnUpdateDeviceResourceError,
-                   AsWeakPtr()));
+    GetDeviceInfo(base::Bind(&DeviceRegistrationInfo::OnDeviceInfoRetrieved,
+                             AsWeakPtr()));
     return;
   }
 
@@ -1015,28 +961,24 @@
   // call to UpdateDeviceResource(), we do not modify the list we are iterating
   // over.
   auto callback_list = std::move(in_progress_resource_update_callbacks_);
-  for (const auto& callback_pair : callback_list)
-    callback_pair.second.Run(error->Clone());
+  for (const auto& callback : callback_list)
+    callback.Run(error->Clone());
 
   StartQueuedUpdateDeviceResource();
 }
 
-void DeviceRegistrationInfo::OnFetchCommandsSuccess(
-    const base::Callback<void(const base::ListValue&)>& callback,
-    const base::DictionaryValue& json) {
+void DeviceRegistrationInfo::OnFetchCommandsDone(
+    const base::Callback<void(const base::ListValue&, ErrorPtr)>& callback,
+    const base::DictionaryValue& json,
+    ErrorPtr error) {
   OnFetchCommandsReturned();
+  if (error)
+    return callback.Run({}, std::move(error));
   const base::ListValue* commands{nullptr};
-  if (!json.GetList("commands", &commands)) {
+  if (!json.GetList("commands", &commands))
     VLOG(2) << "No commands in the response.";
-  }
   const base::ListValue empty;
-  callback.Run(commands ? *commands : empty);
-}
-
-void DeviceRegistrationInfo::OnFetchCommandsError(const ErrorCallback& callback,
-                                                  ErrorPtr error) {
-  OnFetchCommandsReturned();
-  callback.Run(std::move(error));
+  callback.Run(commands ? *commands : empty, nullptr);
 }
 
 void DeviceRegistrationInfo::OnFetchCommandsReturned() {
@@ -1047,17 +989,15 @@
 }
 
 void DeviceRegistrationInfo::FetchCommands(
-    const base::Callback<void(const base::ListValue&)>& on_success,
-    const ErrorCallback& on_failure) {
+    const base::Callback<void(const base::ListValue&, ErrorPtr error)>&
+        callback) {
   fetch_commands_request_sent_ = true;
   fetch_commands_request_queued_ = false;
   DoCloudRequest(
       HttpClient::Method::kGet,
       GetServiceURL("commands/queue", {{"deviceId", GetSettings().cloud_id}}),
-      nullptr, base::Bind(&DeviceRegistrationInfo::OnFetchCommandsSuccess,
-                          AsWeakPtr(), on_success),
-      base::Bind(&DeviceRegistrationInfo::OnFetchCommandsError, AsWeakPtr(),
-                 on_failure));
+      nullptr, base::Bind(&DeviceRegistrationInfo::OnFetchCommandsDone,
+                          AsWeakPtr(), callback));
 }
 
 void DeviceRegistrationInfo::FetchAndPublishCommands() {
@@ -1067,12 +1007,14 @@
   }
 
   FetchCommands(base::Bind(&DeviceRegistrationInfo::PublishCommands,
-                           weak_factory_.GetWeakPtr()),
-                base::Bind(&IgnoreCloudError));
+                           weak_factory_.GetWeakPtr()));
 }
 
 void DeviceRegistrationInfo::ProcessInitialCommandList(
-    const base::ListValue& commands) {
+    const base::ListValue& commands,
+    ErrorPtr error) {
+  if (error)
+    return;
   for (const base::Value* command : commands) {
     const base::DictionaryValue* command_dict{nullptr};
     if (!command->GetAsDictionary(&command_dict)) {
@@ -1098,8 +1040,7 @@
       // TODO(wiley) We could consider handling this error case more gracefully.
       DoCloudRequest(HttpClient::Method::kPut,
                      GetServiceURL("commands/" + command_id), cmd_copy.get(),
-                     base::Bind(&IgnoreCloudResult),
-                     base::Bind(&IgnoreCloudError));
+                     base::Bind(&IgnoreCloudResult));
     } else {
       // Normal command, publish it to local clients.
       PublishCommand(*command_dict);
@@ -1107,7 +1048,10 @@
   }
 }
 
-void DeviceRegistrationInfo::PublishCommands(const base::ListValue& commands) {
+void DeviceRegistrationInfo::PublishCommands(const base::ListValue& commands,
+                                             ErrorPtr error) {
+  if (error)
+    return;
   for (const base::Value* command : commands) {
     const base::DictionaryValue* command_dict{nullptr};
     if (!command->GetAsDictionary(&command_dict)) {
@@ -1188,28 +1132,26 @@
   body.Set("patches", patches.release());
 
   device_state_update_pending_ = true;
-  DoCloudRequest(
-      HttpClient::Method::kPost, GetDeviceURL("patchState"), &body,
-      base::Bind(&DeviceRegistrationInfo::OnPublishStateSuccess, AsWeakPtr(),
-                 update_id),
-      base::Bind(&DeviceRegistrationInfo::OnPublishStateError, AsWeakPtr()));
+  DoCloudRequest(HttpClient::Method::kPost, GetDeviceURL("patchState"), &body,
+                 base::Bind(&DeviceRegistrationInfo::OnPublishStateDone,
+                            AsWeakPtr(), update_id));
 }
 
-void DeviceRegistrationInfo::OnPublishStateSuccess(
+void DeviceRegistrationInfo::OnPublishStateDone(
     StateChangeQueueInterface::UpdateID update_id,
-    const base::DictionaryValue& reply) {
+    const base::DictionaryValue& reply,
+    ErrorPtr error) {
   device_state_update_pending_ = false;
+  if (error) {
+    LOG(ERROR) << "Permanent failure while trying to update device state";
+    return;
+  }
   state_manager_->NotifyStateUpdatedOnServer(update_id);
   // See if there were more pending state updates since the previous request
   // had been sent out.
   PublishStateUpdates();
 }
 
-void DeviceRegistrationInfo::OnPublishStateError(ErrorPtr error) {
-  LOG(ERROR) << "Permanent failure while trying to update device state";
-  device_state_update_pending_ = false;
-}
-
 void DeviceRegistrationInfo::SetGcdState(GcdState new_state) {
   VLOG_IF(1, new_state != gcd_state_) << "Changing registration status to "
                                       << EnumToString(new_state);
@@ -1223,8 +1165,7 @@
   if (!HaveRegistrationCredentials() || !connected_to_cloud_)
     return;
 
-  UpdateDeviceResource(base::Bind(&base::DoNothing),
-                       base::Bind(&IgnoreCloudError));
+  UpdateDeviceResource(base::Bind(&IgnoreCloudError));
 }
 
 void DeviceRegistrationInfo::OnStateChanged() {
@@ -1257,8 +1198,9 @@
   // the moment of the last poll and the time we successfully told the server
   // to send new commands over the new notification channel.
   UpdateDeviceResource(
-      base::Bind(&DeviceRegistrationInfo::FetchAndPublishCommands, AsWeakPtr()),
-      base::Bind(&IgnoreCloudError));
+      base::Bind(&IgnoreCloudErrorWithCallback,
+                 base::Bind(&DeviceRegistrationInfo::FetchAndPublishCommands,
+                            AsWeakPtr())));
 }
 
 void DeviceRegistrationInfo::OnDisconnected() {
@@ -1269,15 +1211,13 @@
   pull_channel_->UpdatePullInterval(
       base::TimeDelta::FromSeconds(kPollingPeriodSeconds));
   current_notification_channel_ = pull_channel_.get();
-  UpdateDeviceResource(base::Bind(&base::DoNothing),
-                       base::Bind(&IgnoreCloudError));
+  UpdateDeviceResource(base::Bind(&IgnoreCloudError));
 }
 
 void DeviceRegistrationInfo::OnPermanentFailure() {
   LOG(ERROR) << "Failed to establish notification channel.";
   notification_channel_starting_ = false;
   RefreshAccessToken(
-      base::Bind(&base::DoNothing),
       base::Bind(&DeviceRegistrationInfo::CheckAccessTokenError, AsWeakPtr()));
 }
 

diff --git a/libweave/src/device_registration_info.h b/libweave/src/device_registration_info.h
index a7f79b6..d389290 100644
--- a/libweave/src/device_registration_info.h
+++ b/libweave/src/device_registration_info.h

@@ -50,8 +50,9 @@
 class DeviceRegistrationInfo : public NotificationDelegate,
                                public CloudCommandUpdateInterface {
  public:
-  using CloudRequestCallback =
-      base::Callback<void(const base::DictionaryValue& response)>;
+  using CloudRequestDoneCallback =
+      base::Callback<void(const base::DictionaryValue& response,
+                          ErrorPtr error)>;
 
   DeviceRegistrationInfo(const std::shared_ptr<CommandManager>& command_manager,
                          const std::shared_ptr<StateManager>& state_manager,
@@ -65,8 +66,7 @@
   void AddGcdStateChangedCallback(
       const Device::GcdStateChangedCallback& callback);
   void RegisterDevice(const std::string& ticket_id,
-                      const SuccessCallback& success_callback,
-                      const ErrorCallback& error_callback);
+                      const DoneCallback& callback);
 
   void UpdateDeviceInfo(const std::string& name,
                         const std::string& description,
@@ -81,8 +81,7 @@
                            const std::string& service_url,
                            ErrorPtr* error);
 
-  void GetDeviceInfo(const CloudRequestCallback& success_callback,
-                     const ErrorCallback& error_callback);
+  void GetDeviceInfo(const CloudRequestDoneCallback& callback);
 
   // Returns the GCD service request URL. If |subpath| is specified, it is
   // appended to the base URL which is normally
@@ -120,8 +119,7 @@
   // Updates a command (override from CloudCommandUpdateInterface).
   void UpdateCommand(const std::string& command_id,
                      const base::DictionaryValue& command_patch,
-                     const base::Closure& on_success,
-                     const base::Closure& on_error) override;
+                     const DoneCallback& callback) override;
 
   // TODO(vitalybuka): remove getters and pass config to dependent code.
   const Config::Settings& GetSettings() const { return config_->GetSettings(); }
@@ -143,22 +141,17 @@
   // Initiates the connection to the cloud server.
   // Device will do required start up chores and then start to listen
   // to new commands.
-  void ConnectToCloud();
+  void ConnectToCloud(ErrorPtr error);
   // Notification called when ConnectToCloud() succeeds.
-  void OnConnectedToCloud();
+  void OnConnectedToCloud(ErrorPtr error);
 
   // Forcibly refreshes the access token.
-  void RefreshAccessToken(const base::Closure& success_callback,
-                          const ErrorCallback& error_callback);
+  void RefreshAccessToken(const DoneCallback& callback);
 
   // Callbacks for RefreshAccessToken().
-  void OnRefreshAccessTokenSuccess(
-      const std::shared_ptr<base::Closure>& success_callback,
-      const std::shared_ptr<ErrorCallback>& error_callback,
-      const provider::HttpClient::Response& response);
-  void OnRefreshAccessTokenError(
-      const std::shared_ptr<base::Closure>& success_callback,
-      const std::shared_ptr<ErrorCallback>& error_callback,
+  void OnRefreshAccessTokenDone(
+      const DoneCallback& callback,
+      std::unique_ptr<provider::HttpClient::Response> response,
       ErrorPtr error);
 
   // Parse the OAuth response, and sets registration status to
@@ -179,40 +172,36 @@
   void DoCloudRequest(provider::HttpClient::Method method,
                       const std::string& url,
                       const base::DictionaryValue* body,
-                      const CloudRequestCallback& success_callback,
-                      const ErrorCallback& error_callback);
+                      const CloudRequestDoneCallback& callback);
 
   // Helper for DoCloudRequest().
   struct CloudRequestData {
     provider::HttpClient::Method method;
     std::string url;
     std::string body;
-    CloudRequestCallback success_callback;
-    ErrorCallback error_callback;
+    CloudRequestDoneCallback callback;
   };
   void SendCloudRequest(const std::shared_ptr<const CloudRequestData>& data);
-  void OnCloudRequestSuccess(
+  void OnCloudRequestDone(
       const std::shared_ptr<const CloudRequestData>& data,
-      const provider::HttpClient::Response& response);
-  void OnCloudRequestError(const std::shared_ptr<const CloudRequestData>& data,
-                           ErrorPtr error);
+      std::unique_ptr<provider::HttpClient::Response> response,
+      ErrorPtr error);
   void RetryCloudRequest(const std::shared_ptr<const CloudRequestData>& data);
   void OnAccessTokenRefreshed(
-      const std::shared_ptr<const CloudRequestData>& data);
-  void OnAccessTokenError(const std::shared_ptr<const CloudRequestData>& data,
-                          ErrorPtr error);
+      const std::shared_ptr<const CloudRequestData>& data,
+      ErrorPtr error);
   void CheckAccessTokenError(ErrorPtr error);
 
-  void UpdateDeviceResource(const base::Closure& on_success,
-                            const ErrorCallback& on_failure);
+  void UpdateDeviceResource(const DoneCallback& callback);
   void StartQueuedUpdateDeviceResource();
-  // Success/failure callbacks for UpdateDeviceResource().
-  void OnUpdateDeviceResourceSuccess(const base::DictionaryValue& device_info);
+  void OnUpdateDeviceResourceDone(const base::DictionaryValue& device_info,
+                                  ErrorPtr error);
   void OnUpdateDeviceResourceError(ErrorPtr error);
 
   // Callback from GetDeviceInfo() to retrieve the device resource timestamp
   // and retry UpdateDeviceResource() call.
-  void OnDeviceInfoRetrieved(const base::DictionaryValue& device_info);
+  void OnDeviceInfoRetrieved(const base::DictionaryValue& device_info,
+                             ErrorPtr error);
 
   // Extracts the timestamp from the device resource and sets it to
   // |last_device_resource_updated_timestamp_|.
@@ -221,13 +210,11 @@
   bool UpdateDeviceInfoTimestamp(const base::DictionaryValue& device_info);
 
   void FetchCommands(
-      const base::Callback<void(const base::ListValue&)>& on_success,
-      const ErrorCallback& on_failure);
-  // Success/failure callbacks for FetchCommands().
-  void OnFetchCommandsSuccess(
-      const base::Callback<void(const base::ListValue&)>& callback,
-      const base::DictionaryValue& json);
-  void OnFetchCommandsError(const ErrorCallback& callback, ErrorPtr error);
+      const base::Callback<void(const base::ListValue&, ErrorPtr)>& callback);
+  void OnFetchCommandsDone(
+      const base::Callback<void(const base::ListValue&, ErrorPtr)>& callback,
+      const base::DictionaryValue& json,
+      ErrorPtr);
   // Called when FetchCommands completes (with either success or error).
   // This method reschedules any pending/queued fetch requests.
   void OnFetchCommandsReturned();
@@ -235,9 +222,10 @@
   // Processes the command list that is fetched from the server on connection.
   // Aborts commands which are in transitional states and publishes queued
   // commands which are queued.
-  void ProcessInitialCommandList(const base::ListValue& commands);
+  void ProcessInitialCommandList(const base::ListValue& commands,
+                                 ErrorPtr error);
 
-  void PublishCommands(const base::ListValue& commands);
+  void PublishCommands(const base::ListValue& commands, ErrorPtr error);
   void PublishCommand(const base::DictionaryValue& command);
 
   // Helper function to pull the pending command list from the server using
@@ -245,8 +233,9 @@
   void FetchAndPublishCommands();
 
   void PublishStateUpdates();
-  void OnPublishStateSuccess(StateChangeQueueInterface::UpdateID update_id,
-                             const base::DictionaryValue& reply);
+  void OnPublishStateDone(StateChangeQueueInterface::UpdateID update_id,
+                          const base::DictionaryValue& reply,
+                          ErrorPtr error);
   void OnPublishStateError(ErrorPtr error);
 
   // If unrecoverable error occurred (e.g. error parsing command instance),
@@ -275,21 +264,22 @@
   // Wipes out the device registration information and stops server connections.
   void MarkDeviceUnregistered();
 
-  struct RegisterCallbacks;
-  void RegisterDeviceError(const std::shared_ptr<RegisterCallbacks>& callbacks,
-                           ErrorPtr error);
+  void RegisterDeviceError(const DoneCallback& callback, ErrorPtr error);
   void RegisterDeviceOnTicketSent(
       const std::string& ticket_id,
-      const std::shared_ptr<RegisterCallbacks>& callbacks,
-      const provider::HttpClient::Response& response);
+      const DoneCallback& callback,
+      std::unique_ptr<provider::HttpClient::Response> response,
+      ErrorPtr error);
   void RegisterDeviceOnTicketFinalized(
-      const std::shared_ptr<RegisterCallbacks>& callbacks,
-      const provider::HttpClient::Response& response);
+      const DoneCallback& callback,
+      std::unique_ptr<provider::HttpClient::Response> response,
+      ErrorPtr error);
   void RegisterDeviceOnAuthCodeSent(
       const std::string& cloud_id,
       const std::string& robot_account,
-      const std::shared_ptr<RegisterCallbacks>& callbacks,
-      const provider::HttpClient::Response& response);
+      const DoneCallback& callback,
+      std::unique_ptr<provider::HttpClient::Response> response,
+      ErrorPtr error);
 
   // Transient data
   std::string access_token_;
@@ -327,13 +317,12 @@
   // another one was in flight.
   bool fetch_commands_request_queued_{false};
 
-  using ResourceUpdateCallbackList =
-      std::vector<std::pair<base::Closure, ErrorCallback>>;
-  // Success/error callbacks for device resource update request currently in
-  // flight to the cloud server.
+  using ResourceUpdateCallbackList = std::vector<DoneCallback>;
+  // Callbacks for device resource update request currently in flight to the
+  // cloud server.
   ResourceUpdateCallbackList in_progress_resource_update_callbacks_;
-  // Success/error callbacks for device resource update requests queued while
-  // another request is in flight to the cloud server.
+  // Callbacks for device resource update requests queued while another request
+  // is in flight to the cloud server.
   ResourceUpdateCallbackList queued_resource_update_callbacks_;
 
   std::unique_ptr<NotificationChannel> primary_notification_channel_;

diff --git a/libweave/src/device_registration_info_unittest.cc b/libweave/src/device_registration_info_unittest.cc
index 6d00a51..b086f8b 100644
--- a/libweave/src/device_registration_info_unittest.cc
+++ b/libweave/src/device_registration_info_unittest.cc

@@ -166,18 +166,19 @@
   }
 
   void PublishCommands(const base::ListValue& commands) {
-    return dev_reg_->PublishCommands(commands);
+    dev_reg_->PublishCommands(commands, nullptr);
   }
 
   bool RefreshAccessToken(ErrorPtr* error) const {
     bool succeeded = false;
-    auto on_success = [&succeeded]() { succeeded = true; };
-    auto on_failure = [&error](ErrorPtr in_error) {
-      if (error)
+    auto callback = [&succeeded, &error](ErrorPtr in_error) {
+      if (error) {
         *error = std::move(in_error);
+        return;
+      }
+      succeeded = true;
     };
-    dev_reg_->RefreshAccessToken(base::Bind(on_success),
-                                 base::Bind(on_failure));
+    dev_reg_->RefreshAccessToken(base::Bind(callback));
     return succeeded;
   }
 
@@ -236,10 +237,10 @@
   EXPECT_CALL(
       http_client_,
       SendRequest(HttpClient::Method::kPost, dev_reg_->GetOAuthURL("token"),
-                  HttpClient::Headers{GetFormHeader()}, _, _, _))
+                  HttpClient::Headers{GetFormHeader()}, _, _))
       .WillOnce(WithArgs<3, 4>(Invoke([](
           const std::string& data,
-          const HttpClient::SuccessCallback& callback) {
+          const HttpClient::SendRequestCallback& callback) {
         EXPECT_EQ("refresh_token", GetFormField(data, "grant_type"));
         EXPECT_EQ(test_data::kRefreshToken,
                   GetFormField(data, "refresh_token"));
@@ -251,7 +252,7 @@
         json.SetString("access_token", test_data::kAccessToken);
         json.SetInteger("expires_in", 3600);
 
-        callback.Run(*ReplyWithJson(200, json));
+        callback.Run(ReplyWithJson(200, json), nullptr);
       })));
 
   EXPECT_TRUE(RefreshAccessToken(nullptr));
@@ -265,10 +266,10 @@
   EXPECT_CALL(
       http_client_,
       SendRequest(HttpClient::Method::kPost, dev_reg_->GetOAuthURL("token"),
-                  HttpClient::Headers{GetFormHeader()}, _, _, _))
+                  HttpClient::Headers{GetFormHeader()}, _, _))
       .WillOnce(WithArgs<3, 4>(Invoke([](
           const std::string& data,
-          const HttpClient::SuccessCallback& callback) {
+          const HttpClient::SendRequestCallback& callback) {
         EXPECT_EQ("refresh_token", GetFormField(data, "grant_type"));
         EXPECT_EQ(test_data::kRefreshToken,
                   GetFormField(data, "refresh_token"));
@@ -278,7 +279,7 @@
 
         base::DictionaryValue json;
         json.SetString("error", "unable_to_authenticate");
-        callback.Run(*ReplyWithJson(400, json));
+        callback.Run(ReplyWithJson(400, json), nullptr);
       })));
 
   ErrorPtr error;
@@ -294,10 +295,10 @@
   EXPECT_CALL(
       http_client_,
       SendRequest(HttpClient::Method::kPost, dev_reg_->GetOAuthURL("token"),
-                  HttpClient::Headers{GetFormHeader()}, _, _, _))
+                  HttpClient::Headers{GetFormHeader()}, _, _))
       .WillOnce(WithArgs<3, 4>(Invoke([](
           const std::string& data,
-          const HttpClient::SuccessCallback& callback) {
+          const HttpClient::SendRequestCallback& callback) {
         EXPECT_EQ("refresh_token", GetFormField(data, "grant_type"));
         EXPECT_EQ(test_data::kRefreshToken,
                   GetFormField(data, "refresh_token"));
@@ -307,7 +308,7 @@
 
         base::DictionaryValue json;
         json.SetString("error", "invalid_grant");
-        callback.Run(*ReplyWithJson(400, json));
+        callback.Run(ReplyWithJson(400, json), nullptr);
       })));
 
   ErrorPtr error;
@@ -320,30 +321,31 @@
   ReloadSettings();
   SetAccessToken();
 
-  EXPECT_CALL(http_client_,
-              SendRequest(HttpClient::Method::kGet, dev_reg_->GetDeviceURL(),
-                          HttpClient::Headers{GetAuthHeader(), GetJsonHeader()},
-                          _, _, _))
+  EXPECT_CALL(
+      http_client_,
+      SendRequest(HttpClient::Method::kGet, dev_reg_->GetDeviceURL(),
+                  HttpClient::Headers{GetAuthHeader(), GetJsonHeader()}, _, _))
       .WillOnce(WithArgs<3, 4>(
           Invoke([](const std::string& data,
-                    const HttpClient::SuccessCallback& callback) {
+                    const HttpClient::SendRequestCallback& callback) {
             base::DictionaryValue json;
             json.SetString("channel.supportedType", "xmpp");
             json.SetString("deviceKind", "vendor");
             json.SetString("id", test_data::kDeviceId);
             json.SetString("kind", "clouddevices#device");
-            callback.Run(*ReplyWithJson(200, json));
+            callback.Run(ReplyWithJson(200, json), nullptr);
           })));
 
   bool succeeded = false;
-  auto on_success = [&succeeded, this](const base::DictionaryValue& info) {
+  auto callback = [&succeeded, this](const base::DictionaryValue& info,
+                                     ErrorPtr error) {
+    EXPECT_FALSE(error);
     std::string id;
     EXPECT_TRUE(info.GetString("id", &id));
     EXPECT_EQ(test_data::kDeviceId, id);
     succeeded = true;
   };
-  auto on_failure = [](ErrorPtr error) { FAIL() << "Should not be called"; };
-  dev_reg_->GetDeviceInfo(base::Bind(on_success), base::Bind(on_failure));
+  dev_reg_->GetDeviceInfo(base::Bind(callback));
   EXPECT_TRUE(succeeded);
 }
 
@@ -386,10 +388,10 @@
   EXPECT_CALL(http_client_,
               SendRequest(HttpClient::Method::kPatch,
                           ticket_url + "?key=" + test_data::kApiKey,
-                          HttpClient::Headers{GetJsonHeader()}, _, _, _))
+                          HttpClient::Headers{GetJsonHeader()}, _, _))
       .WillOnce(WithArgs<3, 4>(Invoke([](
           const std::string& data,
-          const HttpClient::SuccessCallback& callback) {
+          const HttpClient::SendRequestCallback& callback) {
         auto json = test::CreateDictionaryValue(data);
         EXPECT_NE(nullptr, json.get());
         std::string value;
@@ -449,15 +451,15 @@
         device_draft->SetString("kind", "clouddevices#device");
         json_resp.Set("deviceDraft", device_draft);
 
-        callback.Run(*ReplyWithJson(200, json_resp));
+        callback.Run(ReplyWithJson(200, json_resp), nullptr);
       })));
 
   EXPECT_CALL(http_client_,
               SendRequest(HttpClient::Method::kPost,
                           ticket_url + "/finalize?key=" + test_data::kApiKey,
-                          HttpClient::Headers{}, _, _, _))
-      .WillOnce(
-          WithArgs<4>(Invoke([](const HttpClient::SuccessCallback& callback) {
+                          HttpClient::Headers{}, _, _))
+      .WillOnce(WithArgs<4>(
+          Invoke([](const HttpClient::SendRequestCallback& callback) {
             base::DictionaryValue json;
             json.SetString("id", test_data::kClaimTicketId);
             json.SetString("kind", "clouddevices#registrationTicket");
@@ -469,16 +471,16 @@
             json.SetString("robotAccountEmail", test_data::kRobotAccountEmail);
             json.SetString("robotAccountAuthorizationCode",
                            test_data::kRobotAccountAuthCode);
-            callback.Run(*ReplyWithJson(200, json));
+            callback.Run(ReplyWithJson(200, json), nullptr);
           })));
 
   EXPECT_CALL(
       http_client_,
       SendRequest(HttpClient::Method::kPost, dev_reg_->GetOAuthURL("token"),
-                  HttpClient::Headers{GetFormHeader()}, _, _, _))
+                  HttpClient::Headers{GetFormHeader()}, _, _))
       .WillOnce(WithArgs<3, 4>(Invoke([](
           const std::string& data,
-          const HttpClient::SuccessCallback& callback) {
+          const HttpClient::SendRequestCallback& callback) {
         EXPECT_EQ("authorization_code", GetFormField(data, "grant_type"));
         EXPECT_EQ(test_data::kRobotAccountAuthCode, GetFormField(data, "code"));
         EXPECT_EQ(test_data::kClientId, GetFormField(data, "client_id"));
@@ -495,12 +497,13 @@
         json.SetString("refresh_token", test_data::kRefreshToken);
         json.SetInteger("expires_in", 3600);
 
-        callback.Run(*ReplyWithJson(200, json));
+        callback.Run(ReplyWithJson(200, json), nullptr);
       })));
 
   bool done = false;
   dev_reg_->RegisterDevice(
-      test_data::kClaimTicketId, base::Bind([this, &done]() {
+      test_data::kClaimTicketId, base::Bind([this, &done](ErrorPtr error) {
+        EXPECT_FALSE(error);
         done = true;
         task_runner_.Break();
         EXPECT_EQ(GcdState::kConnecting, GetGcdState());
@@ -511,8 +514,7 @@
                   dev_reg_->GetSettings().refresh_token);
         EXPECT_EQ(test_data::kRobotAccountEmail,
                   dev_reg_->GetSettings().robot_account);
-      }),
-      base::Bind([](ErrorPtr error) { ADD_FAILURE(); }));
+      }));
   task_runner_.Run();
   EXPECT_TRUE(done);
 }
@@ -573,51 +575,51 @@
 };
 
 TEST_F(DeviceRegistrationInfoUpdateCommandTest, SetProgress) {
-  EXPECT_CALL(http_client_,
-              SendRequest(HttpClient::Method::kPatch, command_url_,
-                          HttpClient::Headers{GetAuthHeader(), GetJsonHeader()},
-                          _, _, _))
+  EXPECT_CALL(
+      http_client_,
+      SendRequest(HttpClient::Method::kPatch, command_url_,
+                  HttpClient::Headers{GetAuthHeader(), GetJsonHeader()}, _, _))
       .WillOnce(WithArgs<3, 4>(Invoke([](
           const std::string& data,
-          const HttpClient::SuccessCallback& callback) {
+          const HttpClient::SendRequestCallback& callback) {
         EXPECT_JSON_EQ((R"({"state":"inProgress","progress":{"progress":18}})"),
                        *CreateDictionaryValue(data));
         base::DictionaryValue json;
-        callback.Run(*ReplyWithJson(200, json));
+        callback.Run(ReplyWithJson(200, json), nullptr);
       })));
   EXPECT_TRUE(command_->SetProgress(*CreateDictionaryValue("{'progress':18}"),
                                     nullptr));
 }
 
 TEST_F(DeviceRegistrationInfoUpdateCommandTest, Complete) {
-  EXPECT_CALL(http_client_,
-              SendRequest(HttpClient::Method::kPatch, command_url_,
-                          HttpClient::Headers{GetAuthHeader(), GetJsonHeader()},
-                          _, _, _))
+  EXPECT_CALL(
+      http_client_,
+      SendRequest(HttpClient::Method::kPatch, command_url_,
+                  HttpClient::Headers{GetAuthHeader(), GetJsonHeader()}, _, _))
       .WillOnce(WithArgs<3, 4>(Invoke([](
           const std::string& data,
-          const HttpClient::SuccessCallback& callback) {
+          const HttpClient::SendRequestCallback& callback) {
         EXPECT_JSON_EQ(R"({"state":"done", "results":{"status":"Ok"}})",
                        *CreateDictionaryValue(data));
         base::DictionaryValue json;
-        callback.Run(*ReplyWithJson(200, json));
+        callback.Run(ReplyWithJson(200, json), nullptr);
       })));
   EXPECT_TRUE(
       command_->Complete(*CreateDictionaryValue("{'status': 'Ok'}"), nullptr));
 }
 
 TEST_F(DeviceRegistrationInfoUpdateCommandTest, Cancel) {
-  EXPECT_CALL(http_client_,
-              SendRequest(HttpClient::Method::kPatch, command_url_,
-                          HttpClient::Headers{GetAuthHeader(), GetJsonHeader()},
-                          _, _, _))
+  EXPECT_CALL(
+      http_client_,
+      SendRequest(HttpClient::Method::kPatch, command_url_,
+                  HttpClient::Headers{GetAuthHeader(), GetJsonHeader()}, _, _))
       .WillOnce(WithArgs<3, 4>(Invoke([](
           const std::string& data,
-          const HttpClient::SuccessCallback& callback) {
+          const HttpClient::SendRequestCallback& callback) {
         EXPECT_JSON_EQ(R"({"state":"cancelled"})",
                        *CreateDictionaryValue(data));
         base::DictionaryValue json;
-        callback.Run(*ReplyWithJson(200, json));
+        callback.Run(ReplyWithJson(200, json), nullptr);
       })));
   EXPECT_TRUE(command_->Cancel(nullptr));
 }

diff --git a/libweave/src/notification/xmpp_channel.cc b/libweave/src/notification/xmpp_channel.cc
index 0d22286..c88ba45 100644
--- a/libweave/src/notification/xmpp_channel.cc
+++ b/libweave/src/notification/xmpp_channel.cc

@@ -106,10 +106,12 @@
   }
 }
 
-void XmppChannel::OnMessageRead(size_t size) {
+void XmppChannel::OnMessageRead(size_t size, ErrorPtr error) {
+  read_pending_ = false;
+  if (error)
+    return Restart();
   std::string msg(read_socket_data_.data(), size);
   VLOG(2) << "Received XMPP packet: '" << msg << "'";
-  read_pending_ = false;
 
   if (!size)
     return Restart();
@@ -286,14 +288,24 @@
   LOG(INFO) << "Starting XMPP connection to " << kDefaultXmppHost << ":"
             << kDefaultXmppPort;
 
-  network_->OpenSslSocket(
-      kDefaultXmppHost, kDefaultXmppPort,
-      base::Bind(&XmppChannel::OnSslSocketReady,
-                 task_ptr_factory_.GetWeakPtr()),
-      base::Bind(&XmppChannel::OnSslError, task_ptr_factory_.GetWeakPtr()));
+  network_->OpenSslSocket(kDefaultXmppHost, kDefaultXmppPort,
+                          base::Bind(&XmppChannel::OnSslSocketReady,
+                                     task_ptr_factory_.GetWeakPtr()));
 }
 
-void XmppChannel::OnSslSocketReady(std::unique_ptr<Stream> stream) {
+void XmppChannel::OnSslSocketReady(std::unique_ptr<Stream> stream,
+                                   ErrorPtr error) {
+  if (error) {
+    LOG(ERROR) << "TLS handshake failed. Restarting XMPP connection";
+    backoff_entry_.InformOfRequest(false);
+
+    LOG(INFO) << "Delaying connection to XMPP server for "
+              << backoff_entry_.GetTimeUntilRelease();
+    return task_runner_->PostDelayedTask(
+        FROM_HERE, base::Bind(&XmppChannel::CreateSslSocket,
+                              task_ptr_factory_.GetWeakPtr()),
+        backoff_entry_.GetTimeUntilRelease());
+  }
   CHECK(XmppState::kConnecting == state_);
   backoff_entry_.InformOfRequest(true);
   stream_ = std::move(stream);
@@ -302,18 +314,6 @@
   ScheduleRegularPing();
 }
 
-void XmppChannel::OnSslError(ErrorPtr error) {
-  LOG(ERROR) << "TLS handshake failed. Restarting XMPP connection";
-  backoff_entry_.InformOfRequest(false);
-
-  LOG(INFO) << "Delaying connection to XMPP server for "
-            << backoff_entry_.GetTimeUntilRelease();
-  task_runner_->PostDelayedTask(
-      FROM_HERE,
-      base::Bind(&XmppChannel::CreateSslSocket, task_ptr_factory_.GetWeakPtr()),
-      backoff_entry_.GetTimeUntilRelease());
-}
-
 void XmppChannel::SendMessage(const std::string& message) {
   CHECK(stream_) << "No XMPP socket stream available";
   if (write_pending_) {
@@ -327,13 +327,13 @@
   write_pending_ = true;
   stream_->Write(
       write_socket_data_.data(), write_socket_data_.size(),
-      base::Bind(&XmppChannel::OnMessageSent, task_ptr_factory_.GetWeakPtr()),
-      base::Bind(&XmppChannel::OnWriteError, task_ptr_factory_.GetWeakPtr()));
+      base::Bind(&XmppChannel::OnMessageSent, task_ptr_factory_.GetWeakPtr()));
 }
 
-void XmppChannel::OnMessageSent() {
-  ErrorPtr error;
+void XmppChannel::OnMessageSent(ErrorPtr error) {
   write_pending_ = false;
+  if (error)
+    return Restart();
   if (queued_write_data_.empty()) {
     WaitForMessage();
   } else {
@@ -348,18 +348,7 @@
   read_pending_ = true;
   stream_->Read(
       read_socket_data_.data(), read_socket_data_.size(),
-      base::Bind(&XmppChannel::OnMessageRead, task_ptr_factory_.GetWeakPtr()),
-      base::Bind(&XmppChannel::OnReadError, task_ptr_factory_.GetWeakPtr()));
-}
-
-void XmppChannel::OnReadError(ErrorPtr error) {
-  read_pending_ = false;
-  Restart();
-}
-
-void XmppChannel::OnWriteError(ErrorPtr error) {
-  write_pending_ = false;
-  Restart();
+      base::Bind(&XmppChannel::OnMessageRead, task_ptr_factory_.GetWeakPtr()));
 }
 
 std::string XmppChannel::GetName() const {

diff --git a/libweave/src/notification/xmpp_channel.h b/libweave/src/notification/xmpp_channel.h
index 814b2a5..a40eca9 100644
--- a/libweave/src/notification/xmpp_channel.h
+++ b/libweave/src/notification/xmpp_channel.h

@@ -97,15 +97,12 @@
   void RestartXmppStream();
 
   void CreateSslSocket();
-  void OnSslSocketReady(std::unique_ptr<Stream> stream);
-  void OnSslError(ErrorPtr error);
+  void OnSslSocketReady(std::unique_ptr<Stream> stream, ErrorPtr error);
 
   void WaitForMessage();
 
-  void OnMessageRead(size_t size);
-  void OnMessageSent();
-  void OnReadError(ErrorPtr error);
-  void OnWriteError(ErrorPtr error);
+  void OnMessageRead(size_t size, ErrorPtr error);
+  void OnMessageSent(ErrorPtr error);
   void Restart();
   void CloseStream();
 

diff --git a/libweave/src/notification/xmpp_channel_unittest.cc b/libweave/src/notification/xmpp_channel_unittest.cc
index c6e0be1..6c334dd 100644
--- a/libweave/src/notification/xmpp_channel_unittest.cc
+++ b/libweave/src/notification/xmpp_channel_unittest.cc

@@ -88,8 +88,9 @@
         stream_{new test::FakeStream{task_runner_}},
         fake_stream_{stream_.get()} {}
 
-  void Connect(const base::Callback<void(std::unique_ptr<Stream>)>& callback) {
-    callback.Run(std::move(stream_));
+  void Connect(const base::Callback<void(std::unique_ptr<Stream>,
+                                         ErrorPtr error)>& callback) {
+    callback.Run(std::move(stream_), nullptr);
   }
 
   XmppState state() const { return state_; }
@@ -121,7 +122,7 @@
 class XmppChannelTest : public ::testing::Test {
  protected:
   XmppChannelTest() {
-    EXPECT_CALL(network_, OpenSslSocket("talk.google.com", 5223, _, _))
+    EXPECT_CALL(network_, OpenSslSocket("talk.google.com", 5223, _))
         .WillOnce(
             WithArgs<2>(Invoke(&xmpp_client_, &FakeXmppChannel::Connect)));
   }

diff --git a/libweave/src/privet/cloud_delegate.cc b/libweave/src/privet/cloud_delegate.cc
index 3df5b86..81b7e33 100644
--- a/libweave/src/privet/cloud_delegate.cc
+++ b/libweave/src/privet/cloud_delegate.cc

@@ -154,8 +154,7 @@
 
   void AddCommand(const base::DictionaryValue& command,
                   const UserInfo& user_info,
-                  const CommandSuccessCallback& success_callback,
-                  const ErrorCallback& error_callback) override {
+                  const CommandDoneCallback& callback) override {
     CHECK(user_info.scope() != AuthScope::kNone);
     CHECK_NE(user_info.user_id(), 0u);
 
@@ -166,44 +165,41 @@
       Error::AddToPrintf(&error, FROM_HERE, errors::kDomain,
                          errors::kInvalidParams, "Invalid role: '%s'",
                          str_scope.c_str());
-      return error_callback.Run(std::move(error));
+      return callback.Run({}, std::move(error));
     }
 
     std::string id;
     if (!command_manager_->AddCommand(command, role, &id, &error))
-      return error_callback.Run(std::move(error));
+      return callback.Run({}, std::move(error));
 
     command_owners_[id] = user_info.user_id();
-    success_callback.Run(*command_manager_->FindCommand(id)->ToJson());
+    callback.Run(*command_manager_->FindCommand(id)->ToJson(), nullptr);
   }
 
   void GetCommand(const std::string& id,
                   const UserInfo& user_info,
-                  const CommandSuccessCallback& success_callback,
-                  const ErrorCallback& error_callback) override {
+                  const CommandDoneCallback& callback) override {
     CHECK(user_info.scope() != AuthScope::kNone);
     ErrorPtr error;
     auto command = GetCommandInternal(id, user_info, &error);
     if (!command)
-      return error_callback.Run(std::move(error));
-    success_callback.Run(*command->ToJson());
+      return callback.Run({}, std::move(error));
+    callback.Run(*command->ToJson(), nullptr);
   }
 
   void CancelCommand(const std::string& id,
                      const UserInfo& user_info,
-                     const CommandSuccessCallback& success_callback,
-                     const ErrorCallback& error_callback) override {
+                     const CommandDoneCallback& callback) override {
     CHECK(user_info.scope() != AuthScope::kNone);
     ErrorPtr error;
     auto command = GetCommandInternal(id, user_info, &error);
     if (!command || !command->Cancel(&error))
-      return error_callback.Run(std::move(error));
-    success_callback.Run(*command->ToJson());
+      return callback.Run({}, std::move(error));
+    callback.Run(*command->ToJson(), nullptr);
   }
 
   void ListCommands(const UserInfo& user_info,
-                    const CommandSuccessCallback& success_callback,
-                    const ErrorCallback& error_callback) override {
+                    const CommandDoneCallback& callback) override {
     CHECK(user_info.scope() != AuthScope::kNone);
 
     base::ListValue list_value;
@@ -218,7 +214,7 @@
     base::DictionaryValue commands_json;
     commands_json.Set("commands", list_value.DeepCopy());
 
-    success_callback.Run(commands_json);
+    callback.Run(commands_json, nullptr);
   }
 
  private:
@@ -285,29 +281,27 @@
     }
 
     device_->RegisterDevice(
-        ticket_id, base::Bind(&CloudDelegateImpl::RegisterDeviceSuccess,
-                              setup_weak_factory_.GetWeakPtr()),
-        base::Bind(&CloudDelegateImpl::RegisterDeviceError,
+        ticket_id,
+        base::Bind(&CloudDelegateImpl::RegisterDeviceDone,
                    setup_weak_factory_.GetWeakPtr(), ticket_id, deadline));
   }
 
-  void RegisterDeviceSuccess() {
+  void RegisterDeviceDone(const std::string& ticket_id,
+                          const base::Time& deadline,
+                          ErrorPtr error) {
+    if (error) {
+      // Registration failed. Retry with backoff.
+      backoff_entry_.InformOfRequest(false);
+      return task_runner_->PostDelayedTask(
+          FROM_HERE,
+          base::Bind(&CloudDelegateImpl::CallManagerRegisterDevice,
+                     setup_weak_factory_.GetWeakPtr(), ticket_id, deadline),
+          backoff_entry_.GetTimeUntilRelease());
+    }
     backoff_entry_.InformOfRequest(true);
     setup_state_ = SetupState(SetupState::kSuccess);
   }
 
-  void RegisterDeviceError(const std::string& ticket_id,
-                           const base::Time& deadline,
-                           ErrorPtr error) {
-    // Registration failed. Retry with backoff.
-    backoff_entry_.InformOfRequest(false);
-    task_runner_->PostDelayedTask(
-        FROM_HERE,
-        base::Bind(&CloudDelegateImpl::CallManagerRegisterDevice,
-                   setup_weak_factory_.GetWeakPtr(), ticket_id, deadline),
-        backoff_entry_.GetTimeUntilRelease());
-  }
-
   CommandInstance* GetCommandInternal(const std::string& command_id,
                                       const UserInfo& user_info,
                                       ErrorPtr* error) const {

diff --git a/libweave/src/privet/cloud_delegate.h b/libweave/src/privet/cloud_delegate.h
index 74456d3..05ba8a6 100644
--- a/libweave/src/privet/cloud_delegate.h
+++ b/libweave/src/privet/cloud_delegate.h

@@ -39,8 +39,9 @@
   CloudDelegate();
   virtual ~CloudDelegate();
 
-  using CommandSuccessCallback =
-      base::Callback<void(const base::DictionaryValue& commands)>;
+  using CommandDoneCallback =
+      base::Callback<void(const base::DictionaryValue& commands,
+                          ErrorPtr error)>;
 
   class Observer {
    public:
@@ -107,25 +108,21 @@
   // Adds command created from the given JSON representation.
   virtual void AddCommand(const base::DictionaryValue& command,
                           const UserInfo& user_info,
-                          const CommandSuccessCallback& success_callback,
-                          const ErrorCallback& error_callback) = 0;
+                          const CommandDoneCallback& callback) = 0;
 
   // Returns command with the given ID.
   virtual void GetCommand(const std::string& id,
                           const UserInfo& user_info,
-                          const CommandSuccessCallback& success_callback,
-                          const ErrorCallback& error_callback) = 0;
+                          const CommandDoneCallback& callback) = 0;
 
   // Cancels command with the given ID.
   virtual void CancelCommand(const std::string& id,
                              const UserInfo& user_info,
-                             const CommandSuccessCallback& success_callback,
-                             const ErrorCallback& error_callback) = 0;
+                             const CommandDoneCallback& callback) = 0;
 
   // Lists commands.
   virtual void ListCommands(const UserInfo& user_info,
-                            const CommandSuccessCallback& success_callback,
-                            const ErrorCallback& error_callback) = 0;
+                            const CommandDoneCallback& callback) = 0;
 
   void AddObserver(Observer* observer) { observer_list_.AddObserver(observer); }
   void RemoveObserver(Observer* observer) {

diff --git a/libweave/src/privet/mock_delegates.h b/libweave/src/privet/mock_delegates.h
index 48227ae..f16b526 100644
--- a/libweave/src/privet/mock_delegates.h
+++ b/libweave/src/privet/mock_delegates.h

@@ -154,25 +154,19 @@
   MOCK_CONST_METHOD0(GetCloudId, std::string());
   MOCK_CONST_METHOD0(GetState, const base::DictionaryValue&());
   MOCK_CONST_METHOD0(GetCommandDef, const base::DictionaryValue&());
-  MOCK_METHOD4(AddCommand,
+  MOCK_METHOD3(AddCommand,
                void(const base::DictionaryValue&,
                     const UserInfo&,
-                    const CommandSuccessCallback&,
-                    const ErrorCallback&));
-  MOCK_METHOD4(GetCommand,
+                    const CommandDoneCallback&));
+  MOCK_METHOD3(GetCommand,
                void(const std::string&,
                     const UserInfo&,
-                    const CommandSuccessCallback&,
-                    const ErrorCallback&));
-  MOCK_METHOD4(CancelCommand,
+                    const CommandDoneCallback&));
+  MOCK_METHOD3(CancelCommand,
                void(const std::string&,
                     const UserInfo&,
-                    const CommandSuccessCallback&,
-                    const ErrorCallback&));
-  MOCK_METHOD3(ListCommands,
-               void(const UserInfo&,
-                    const CommandSuccessCallback&,
-                    const ErrorCallback&));
+                    const CommandDoneCallback&));
+  MOCK_METHOD2(ListCommands, void(const UserInfo&, const CommandDoneCallback&));
 
   MockCloudDelegate() {
     EXPECT_CALL(*this, GetDeviceId()).WillRepeatedly(Return("TestId"));

diff --git a/libweave/src/privet/privet_handler.cc b/libweave/src/privet/privet_handler.cc
index 702104d..ad1d3d0 100644
--- a/libweave/src/privet/privet_handler.cc
+++ b/libweave/src/privet/privet_handler.cc

@@ -198,23 +198,20 @@
 }
 
 void OnCommandRequestSucceeded(const PrivetHandler::RequestCallback& callback,
-                               const base::DictionaryValue& output) {
-  callback.Run(http::kOk, output);
-}
+                               const base::DictionaryValue& output,
+                               ErrorPtr error) {
+  if (!error)
+    return callback.Run(http::kOk, output);
 
-void OnCommandRequestFailed(const PrivetHandler::RequestCallback& callback,
-                            ErrorPtr error) {
   if (error->HasError("gcd", "unknown_command")) {
-    ErrorPtr new_error = error->Clone();
-    Error::AddTo(&new_error, FROM_HERE, errors::kDomain, errors::kNotFound,
+    Error::AddTo(&error, FROM_HERE, errors::kDomain, errors::kNotFound,
                  "Unknown command ID");
-    return ReturnError(*new_error, callback);
+    return ReturnError(*error, callback);
   }
   if (error->HasError("gcd", "access_denied")) {
-    ErrorPtr new_error = error->Clone();
-    Error::AddTo(&new_error, FROM_HERE, errors::kDomain, errors::kAccessDenied,
+    Error::AddTo(&error, FROM_HERE, errors::kDomain, errors::kAccessDenied,
                  error->GetMessage());
-    return ReturnError(*new_error, callback);
+    return ReturnError(*error, callback);
   }
   return ReturnError(*error, callback);
 }
@@ -768,8 +765,7 @@
                                           const UserInfo& user_info,
                                           const RequestCallback& callback) {
   cloud_->AddCommand(input, user_info,
-                     base::Bind(&OnCommandRequestSucceeded, callback),
-                     base::Bind(&OnCommandRequestFailed, callback));
+                     base::Bind(&OnCommandRequestSucceeded, callback));
 }
 
 void PrivetHandler::HandleCommandsStatus(const base::DictionaryValue& input,
@@ -784,16 +780,14 @@
     return ReturnError(*error, callback);
   }
   cloud_->GetCommand(id, user_info,
-                     base::Bind(&OnCommandRequestSucceeded, callback),
-                     base::Bind(&OnCommandRequestFailed, callback));
+                     base::Bind(&OnCommandRequestSucceeded, callback));
 }
 
 void PrivetHandler::HandleCommandsList(const base::DictionaryValue& input,
                                        const UserInfo& user_info,
                                        const RequestCallback& callback) {
   cloud_->ListCommands(user_info,
-                       base::Bind(&OnCommandRequestSucceeded, callback),
-                       base::Bind(&OnCommandRequestFailed, callback));
+                       base::Bind(&OnCommandRequestSucceeded, callback));
 }
 
 void PrivetHandler::HandleCommandsCancel(const base::DictionaryValue& input,
@@ -808,8 +802,7 @@
     return ReturnError(*error, callback);
   }
   cloud_->CancelCommand(id, user_info,
-                        base::Bind(&OnCommandRequestSucceeded, callback),
-                        base::Bind(&OnCommandRequestFailed, callback));
+                        base::Bind(&OnCommandRequestSucceeded, callback));
 }
 
 }  // namespace privet

diff --git a/libweave/src/privet/privet_handler_unittest.cc b/libweave/src/privet/privet_handler_unittest.cc
index 42dd956..dba394a 100644
--- a/libweave/src/privet/privet_handler_unittest.cc
+++ b/libweave/src/privet/privet_handler_unittest.cc

@@ -649,8 +649,11 @@
   base::DictionaryValue command;
   LoadTestJson(kInput, &command);
   LoadTestJson("{'id':'5'}", &command);
-  EXPECT_CALL(cloud_, AddCommand(_, _, _, _))
-      .WillOnce(RunCallback<2, const base::DictionaryValue&>(command));
+  EXPECT_CALL(cloud_, AddCommand(_, _, _))
+      .WillOnce(WithArgs<2>(Invoke(
+          [&command](const CloudDelegate::CommandDoneCallback& callback) {
+            callback.Run(command, nullptr);
+          })));
 
   EXPECT_PRED2(IsEqualJson, "{'name':'test', 'id':'5'}",
                HandleRequest("/privet/v3/commands/execute", kInput));
@@ -661,18 +664,22 @@
   base::DictionaryValue command;
   LoadTestJson(kInput, &command);
   LoadTestJson("{'name':'test'}", &command);
-  EXPECT_CALL(cloud_, GetCommand(_, _, _, _))
-      .WillOnce(RunCallback<2, const base::DictionaryValue&>(command));
+  EXPECT_CALL(cloud_, GetCommand(_, _, _))
+      .WillOnce(WithArgs<2>(Invoke(
+          [&command](const CloudDelegate::CommandDoneCallback& callback) {
+            callback.Run(command, nullptr);
+          })));
 
   EXPECT_PRED2(IsEqualJson, "{'name':'test', 'id':'5'}",
                HandleRequest("/privet/v3/commands/status", kInput));
 
   ErrorPtr error;
   Error::AddTo(&error, FROM_HERE, errors::kDomain, "notFound", "");
-  EXPECT_CALL(cloud_, GetCommand(_, _, _, _))
-      .WillOnce(WithArgs<3>(Invoke([&error](const ErrorCallback& callback) {
-        callback.Run(std::move(error));
-      })));
+  EXPECT_CALL(cloud_, GetCommand(_, _, _))
+      .WillOnce(WithArgs<2>(
+          Invoke([&error](const CloudDelegate::CommandDoneCallback& callback) {
+            callback.Run({}, std::move(error));
+          })));
 
   EXPECT_PRED2(IsEqualError, CodeWithReason(404, "notFound"),
                HandleRequest("/privet/v3/commands/status", "{'id': '15'}"));
@@ -682,18 +689,22 @@
   const char kExpected[] = "{'id': '5', 'name':'test', 'state':'cancelled'}";
   base::DictionaryValue command;
   LoadTestJson(kExpected, &command);
-  EXPECT_CALL(cloud_, CancelCommand(_, _, _, _))
-      .WillOnce(RunCallback<2, const base::DictionaryValue&>(command));
+  EXPECT_CALL(cloud_, CancelCommand(_, _, _))
+      .WillOnce(WithArgs<2>(Invoke(
+          [&command](const CloudDelegate::CommandDoneCallback& callback) {
+            callback.Run(command, nullptr);
+          })));
 
   EXPECT_PRED2(IsEqualJson, kExpected,
                HandleRequest("/privet/v3/commands/cancel", "{'id': '8'}"));
 
   ErrorPtr error;
   Error::AddTo(&error, FROM_HERE, errors::kDomain, "notFound", "");
-  EXPECT_CALL(cloud_, CancelCommand(_, _, _, _))
-      .WillOnce(WithArgs<3>(Invoke([&error](const ErrorCallback& callback) {
-        callback.Run(std::move(error));
-      })));
+  EXPECT_CALL(cloud_, CancelCommand(_, _, _))
+      .WillOnce(WithArgs<2>(
+          Invoke([&error](const CloudDelegate::CommandDoneCallback& callback) {
+            callback.Run({}, std::move(error));
+          })));
 
   EXPECT_PRED2(IsEqualError, CodeWithReason(404, "notFound"),
                HandleRequest("/privet/v3/commands/cancel", "{'id': '11'}"));
@@ -709,8 +720,11 @@
   base::DictionaryValue commands;
   LoadTestJson(kExpected, &commands);
 
-  EXPECT_CALL(cloud_, ListCommands(_, _, _))
-      .WillOnce(RunCallback<1, const base::DictionaryValue&>(commands));
+  EXPECT_CALL(cloud_, ListCommands(_, _))
+      .WillOnce(WithArgs<1>(Invoke(
+          [&commands](const CloudDelegate::CommandDoneCallback& callback) {
+            callback.Run(commands, nullptr);
+          })));
 
   EXPECT_PRED2(IsEqualJson, kExpected,
                HandleRequest("/privet/v3/commands/list", "{}"));

diff --git a/libweave/src/privet/wifi_bootstrap_manager.cc b/libweave/src/privet/wifi_bootstrap_manager.cc
index b4b0153..1d2d813 100644
--- a/libweave/src/privet/wifi_bootstrap_manager.cc
+++ b/libweave/src/privet/wifi_bootstrap_manager.cc

@@ -96,21 +96,12 @@
           << ", pass=" << passphrase << ").";
   UpdateState(State::kConnecting);
   task_runner_->PostDelayedTask(
-      FROM_HERE, base::Bind(&WifiBootstrapManager::OnConnectError,
-                            tasks_weak_factory_.GetWeakPtr(), nullptr),
+      FROM_HERE, base::Bind(&WifiBootstrapManager::OnConnectTimeout,
+                            tasks_weak_factory_.GetWeakPtr()),
       base::TimeDelta::FromMinutes(3));
   wifi_->Connect(ssid, passphrase,
-                 base::Bind(&WifiBootstrapManager::OnConnectSuccess,
-                            tasks_weak_factory_.GetWeakPtr(), ssid),
-                 base::Bind(&WifiBootstrapManager::OnConnectError,
-                            tasks_weak_factory_.GetWeakPtr()));
-}
-
-void WifiBootstrapManager::OnConnectError(ErrorPtr error) {
-  Error::AddTo(&error, FROM_HERE, errors::kDomain, errors::kInvalidState,
-               "Failed to connect to provided network");
-  setup_state_ = SetupState{std::move(error)};
-  StartBootstrapping();
+                 base::Bind(&WifiBootstrapManager::OnConnectDone,
+                            tasks_weak_factory_.GetWeakPtr(), ssid));
 }
 
 void WifiBootstrapManager::EndConnecting() {}
@@ -203,7 +194,14 @@
   return {WifiType::kWifi24};
 }
 
-void WifiBootstrapManager::OnConnectSuccess(const std::string& ssid) {
+void WifiBootstrapManager::OnConnectDone(const std::string& ssid,
+                                         ErrorPtr error) {
+  if (error) {
+    Error::AddTo(&error, FROM_HERE, errors::kDomain, errors::kInvalidState,
+                 "Failed to connect to provided network");
+    setup_state_ = SetupState{std::move(error)};
+    return StartBootstrapping();
+  }
   VLOG(1) << "Wifi was connected successfully";
   Config::Transaction change{config_};
   change.set_last_configured_ssid(ssid);
@@ -212,6 +210,14 @@
   StartMonitoring();
 }
 
+void WifiBootstrapManager::OnConnectTimeout() {
+  ErrorPtr error;
+  Error::AddTo(&error, FROM_HERE, errors::kDomain, errors::kInvalidState,
+               "Timeout connecting to provided network");
+  setup_state_ = SetupState{std::move(error)};
+  return StartBootstrapping();
+}
+
 void WifiBootstrapManager::OnBootstrapTimeout() {
   VLOG(1) << "Bootstrapping has timed out.";
   StartMonitoring();

diff --git a/libweave/src/privet/wifi_bootstrap_manager.h b/libweave/src/privet/wifi_bootstrap_manager.h
index 390af31..c0a1c24 100644
--- a/libweave/src/privet/wifi_bootstrap_manager.h
+++ b/libweave/src/privet/wifi_bootstrap_manager.h

@@ -87,8 +87,8 @@
   // to return to monitoring mode periodically in case our connectivity issues
   // were temporary.
   void OnBootstrapTimeout();
-  void OnConnectSuccess(const std::string& ssid);
-  void OnConnectError(ErrorPtr error);
+  void OnConnectDone(const std::string& ssid, ErrorPtr error);
+  void OnConnectTimeout();
   void OnConnectivityChange();
   void OnMonitorTimeout();
   void UpdateConnectionState();

diff --git a/libweave/src/streams.cc b/libweave/src/streams.cc
index 1dc0355..0516f66 100644
--- a/libweave/src/streams.cc
+++ b/libweave/src/streams.cc

@@ -19,52 +19,54 @@
 
 void MemoryStream::Read(void* buffer,
                         size_t size_to_read,
-                        const ReadSuccessCallback& success_callback,
-                        const ErrorCallback& error_callback) {
+                        const ReadCallback& callback) {
   CHECK_LE(read_position_, data_.size());
   size_t size_read = std::min(size_to_read, data_.size() - read_position_);
   if (size_read > 0)
     memcpy(buffer, data_.data() + read_position_, size_read);
   read_position_ += size_read;
   task_runner_->PostDelayedTask(FROM_HERE,
-                                base::Bind(success_callback, size_read), {});
+                                base::Bind(callback, size_read, nullptr), {});
 }
 
 void MemoryStream::Write(const void* buffer,
                          size_t size_to_write,
-                         const SuccessCallback& success_callback,
-                         const ErrorCallback& error_callback) {
+                         const WriteCallback& callback) {
   data_.insert(data_.end(), static_cast<const char*>(buffer),
                static_cast<const char*>(buffer) + size_to_write);
-  task_runner_->PostDelayedTask(FROM_HERE, success_callback, {});
+  task_runner_->PostDelayedTask(FROM_HERE, base::Bind(callback, nullptr), {});
 }
 
 StreamCopier::StreamCopier(InputStream* source, OutputStream* destination)
     : source_{source}, destination_{destination}, buffer_(4096) {}
 
-void StreamCopier::Copy(
-    const InputStream::ReadSuccessCallback& success_callback,
-    const ErrorCallback& error_callback) {
-  source_->Read(
-      buffer_.data(), buffer_.size(),
-      base::Bind(&StreamCopier::OnSuccessRead, weak_ptr_factory_.GetWeakPtr(),
-                 success_callback, error_callback),
-      error_callback);
+void StreamCopier::Copy(const InputStream::ReadCallback& callback) {
+  source_->Read(buffer_.data(), buffer_.size(),
+                base::Bind(&StreamCopier::OnReadDone,
+                           weak_ptr_factory_.GetWeakPtr(), callback));
 }
 
-void StreamCopier::OnSuccessRead(
-    const InputStream::ReadSuccessCallback& success_callback,
-    const ErrorCallback& error_callback,
-    size_t size) {
+void StreamCopier::OnReadDone(const InputStream::ReadCallback& callback,
+                              size_t size,
+                              ErrorPtr error) {
+  if (error)
+    return callback.Run(0, std::move(error));
+
   size_done_ += size;
   if (size) {
     return destination_->Write(
         buffer_.data(), size,
-        base::Bind(&StreamCopier::Copy, weak_ptr_factory_.GetWeakPtr(),
-                   success_callback, error_callback),
-        error_callback);
+        base::Bind(&StreamCopier::OnWriteDone, weak_ptr_factory_.GetWeakPtr(),
+                   callback));
   }
-  success_callback.Run(size_done_);
+  callback.Run(size_done_, nullptr);
+}
+
+void StreamCopier::OnWriteDone(const InputStream::ReadCallback& callback,
+                               ErrorPtr error) {
+  if (error)
+    return callback.Run(size_done_, std::move(error));
+  Copy(callback);
 }
 
 }  // namespace weave

diff --git a/libweave/src/streams.h b/libweave/src/streams.h
index 0a21737..6d2a1d0 100644
--- a/libweave/src/streams.h
+++ b/libweave/src/streams.h

@@ -21,13 +21,11 @@
 
   void Read(void* buffer,
             size_t size_to_read,
-            const ReadSuccessCallback& success_callback,
-            const ErrorCallback& error_callback) override;
+            const ReadCallback& callback) override;
 
   void Write(const void* buffer,
              size_t size_to_write,
-             const SuccessCallback& success_callback,
-             const ErrorCallback& error_callback) override;
+             const WriteCallback& callback) override;
 
   const std::vector<uint8_t>& GetData() const { return data_; }
 
@@ -41,13 +39,13 @@
  public:
   StreamCopier(InputStream* source, OutputStream* destination);
 
-  void Copy(const InputStream::ReadSuccessCallback& success_callback,
-            const ErrorCallback& error_callback);
+  void Copy(const InputStream::ReadCallback& callback);
 
  private:
-  void OnSuccessRead(const InputStream::ReadSuccessCallback& success_callback,
-                     const ErrorCallback& error_callback,
-                     size_t size);
+  void OnWriteDone(const InputStream::ReadCallback& callback, ErrorPtr error);
+  void OnReadDone(const InputStream::ReadCallback& callback,
+                  size_t size,
+                  ErrorPtr error);
 
   InputStream* source_{nullptr};
   OutputStream* destination_{nullptr};

diff --git a/libweave/src/streams_unittest.cc b/libweave/src/streams_unittest.cc
index 3cef6f0..b669328 100644
--- a/libweave/src/streams_unittest.cc
+++ b/libweave/src/streams_unittest.cc

@@ -23,13 +23,14 @@
 
   bool done = false;
 
-  auto on_success = base::Bind([&test_data, &done, &destination](size_t size) {
-    done = true;
-    EXPECT_EQ(test_data, destination.GetData());
-  });
-  auto on_error = base::Bind([](ErrorPtr error) { ADD_FAILURE(); });
+  auto callback = base::Bind(
+      [&test_data, &done, &destination](size_t size, ErrorPtr error) {
+        EXPECT_FALSE(error);
+        done = true;
+        EXPECT_EQ(test_data, destination.GetData());
+      });
   StreamCopier copier{&source, &destination};
-  copier.Copy(on_success, on_error);
+  copier.Copy(callback);
 
   task_runner.Run(test_data.size());
   EXPECT_TRUE(done);

diff --git a/libweave/src/test/fake_stream.cc b/libweave/src/test/fake_stream.cc
index 786aa01..7c86c4a 100644
--- a/libweave/src/test/fake_stream.cc
+++ b/libweave/src/test/fake_stream.cc

@@ -30,33 +30,30 @@
 
 void FakeStream::Read(void* buffer,
                       size_t size_to_read,
-                      const ReadSuccessCallback& success_callback,
-                      const ErrorCallback& error_callback) {
+                      const ReadCallback& callback) {
   if (read_data_.empty()) {
     task_runner_->PostDelayedTask(
-        FROM_HERE,
-        base::Bind(&FakeStream::Read, base::Unretained(this), buffer,
-                    size_to_read, success_callback, error_callback),
+        FROM_HERE, base::Bind(&FakeStream::Read, base::Unretained(this), buffer,
+                              size_to_read, callback),
         base::TimeDelta::FromSeconds(0));
     return;
   }
   size_t size = std::min(size_to_read, read_data_.size());
   memcpy(buffer, read_data_.data(), size);
   read_data_ = read_data_.substr(size);
-  task_runner_->PostDelayedTask(FROM_HERE, base::Bind(success_callback, size),
+  task_runner_->PostDelayedTask(FROM_HERE, base::Bind(callback, size, nullptr),
                                 base::TimeDelta::FromSeconds(0));
 }
 
 void FakeStream::Write(const void* buffer,
                        size_t size_to_write,
-                       const SuccessCallback& success_callback,
-                       const ErrorCallback& error_callback) {
+                       const WriteCallback& callback) {
   size_t size = std::min(size_to_write, write_data_.size());
   EXPECT_EQ(
       write_data_.substr(0, size),
       std::string(reinterpret_cast<const char*>(buffer), size_to_write));
   write_data_ = write_data_.substr(size);
-  task_runner_->PostDelayedTask(FROM_HERE, success_callback,
+  task_runner_->PostDelayedTask(FROM_HERE, base::Bind(callback, nullptr),
                                 base::TimeDelta::FromSeconds(0));
 }
 

diff --git a/libweave/src/weave_unittest.cc b/libweave/src/weave_unittest.cc
index 8d87229..74e8c41 100644
--- a/libweave/src/weave_unittest.cc
+++ b/libweave/src/weave_unittest.cc

@@ -140,9 +140,9 @@
   void ExpectRequest(HttpClient::Method method,
                      const std::string& url,
                      const std::string& json_response) {
-    EXPECT_CALL(http_client_, SendRequest(method, url, _, _, _, _))
+    EXPECT_CALL(http_client_, SendRequest(method, url, _, _, _))
         .WillOnce(WithArgs<4>(Invoke([json_response](
-            const HttpClient::SuccessCallback& callback) {
+            const HttpClient::SendRequestCallback& callback) {
           std::unique_ptr<provider::test::MockHttpClientResponse> response{
               new StrictMock<provider::test::MockHttpClientResponse>};
           EXPECT_CALL(*response, GetStatusCode())
@@ -154,7 +154,7 @@
           EXPECT_CALL(*response, GetData())
               .Times(AtLeast(1))
               .WillRepeatedly(Return(json_response));
-          callback.Run(*response);
+          callback.Run(std::move(response), nullptr);
         })));
   }
 
@@ -306,7 +306,7 @@
 }
 
 TEST_F(WeaveBasicTest, Register) {
-  EXPECT_CALL(network_, OpenSslSocket(_, _, _, _)).WillRepeatedly(Return());
+  EXPECT_CALL(network_, OpenSslSocket(_, _, _)).WillRepeatedly(Return());
   StartDevice();
 
   auto draft = CreateDictionaryValue(kDeviceResource);
@@ -333,12 +333,12 @@
   InitDnsSdPublishing(true, "DB");
 
   bool done = false;
-  device_->Register("TICKET_ID", base::Bind([this, &done]() {
+  device_->Register("TICKET_ID", base::Bind([this, &done](ErrorPtr error) {
+                      EXPECT_FALSE(error);
                       done = true;
                       task_runner_.Break();
                       EXPECT_EQ("CLOUD_ID", device_->GetSettings().cloud_id);
-                    }),
-                    base::Bind([](ErrorPtr error) { ADD_FAILURE(); }));
+                    }));
   task_runner_.Run();
   EXPECT_TRUE(done);
 }