diff --git a/examples/daemon/sample/sample.cc b/examples/daemon/sample/sample.cc
index 97cef61..2ab4b27 100644
--- a/examples/daemon/sample/sample.cc
+++ b/examples/daemon/sample/sample.cc
@@ -104,7 +104,7 @@
 
     device_->SetStateProperty(kComponent, "_sample._ping_count",
                               base::FundamentalValue{++ping_count_}, nullptr);
-    LOG(INFO) << "New state: " << device_->GetState();
+    LOG(INFO) << "New component state: " << device_->GetComponents();
 
     base::DictionaryValue result;
     cmd->Complete(result, nullptr);
diff --git a/include/weave/device.h b/include/weave/device.h
index 2d7aaff..99035f4 100644
--- a/include/weave/device.h
+++ b/include/weave/device.h
@@ -53,6 +53,10 @@
   // Returns the full JSON dictionary containing trait definitions.
   virtual const base::DictionaryValue& GetTraits() const = 0;
 
+  // Sets callback which is called when new trait definitions are added.
+  virtual void AddTraitDefsChangedCallback(
+      const base::Closure& callback) = 0;
+
   // Adds a new component instance to device. Traits used by this component
   // must be already defined.
   virtual bool AddComponent(const std::string& name,
@@ -172,6 +176,7 @@
   // Adds provided commands definitions. Can be called multiple times with
   // condition that definitions do not conflict.
   // Invalid value is fatal.
+  // DO NOT USE IN YOUR CODE: use AddTraitDefinitions() instead.
   LIBWEAVE_DEPRECATED virtual void AddCommandDefinitionsFromJson(
       const std::string& json) = 0;
   LIBWEAVE_DEPRECATED virtual void AddCommandDefinitions(
@@ -182,6 +187,7 @@
   // "base.reboot". Each command can have no more than one handler.
   // Empty |command_name| sets default handler for all unhanded commands.
   // No new command handlers can be set after default handler was set.
+  // DO NOT USE IN YOUR CODE: use AddCommandHandler() with component parameter.
   LIBWEAVE_DEPRECATED virtual void AddCommandHandler(
       const std::string& command_name,
       const CommandHandlerCallback& callback) = 0;
@@ -189,6 +195,7 @@
   // Adds provided state definitions. Can be called multiple times with
   // condition that definitions do not conflict.
   // Invalid value is fatal.
+  // DO NOT USE IN YOUR CODE: use AddTraitDefinitions() instead.
   LIBWEAVE_DEPRECATED virtual void AddStateDefinitionsFromJson(
       const std::string& json) = 0;
   LIBWEAVE_DEPRECATED virtual void AddStateDefinitions(
@@ -201,6 +208,7 @@
   //   device->SetStatePropertiesFromJson("{'base':{'firmwareVersion':'123'}}")
   // Method completely replaces properties included |json| or |dict|.
   // Properties of the state not included |json| or |dict| will stay unchanged.
+  // DO NOT USE IN YOUR CODE: use SetStateProperties() with component parameter.
   LIBWEAVE_DEPRECATED virtual bool SetStatePropertiesFromJson(
       const std::string& json,
       ErrorPtr* error) = 0;
@@ -210,19 +218,21 @@
 
   // Returns value of the single property.
   // |name| is full property name, including package name. e.g. "base.network".
+  // DO NOT USE IN YOUR CODE: use GetStateProperty() with component parameter.
   LIBWEAVE_DEPRECATED virtual const base::Value* GetStateProperty(
       const std::string& name) const = 0;
 
   // Sets value of the single property.
   // |name| is full property name, including package name. e.g. "base.network".
+  // DO NOT USE IN YOUR CODE: use SetStateProperty() with component parameter.
   LIBWEAVE_DEPRECATED virtual bool SetStateProperty(
       const std::string& name,
       const base::Value& value,
       ErrorPtr* error) = 0;
 
   // Returns aggregated state properties across all registered packages.
+  // DO NOT USE IN YOUR CODE: use GetComponents() instead.
   LIBWEAVE_DEPRECATED virtual const base::DictionaryValue& GetState() const = 0;
-
 };
 
 }  // namespace weave
diff --git a/include/weave/export.h b/include/weave/export.h
index f698176..6a658f9 100644
--- a/include/weave/export.h
+++ b/include/weave/export.h
@@ -8,8 +8,6 @@
 #define LIBWEAVE_EXPORT __attribute__((__visibility__("default")))
 #define LIBWEAVE_PRIVATE __attribute__((__visibility__("hidden")))
 
-// TODO(avakulenko): Once all the sample clients are migrated to new APIs,
-// mark the old one officially deprecated by uncomment the following attribute.
-#define LIBWEAVE_DEPRECATED // __attribute__((deprecated))
+#define LIBWEAVE_DEPRECATED __attribute__((deprecated))
 
 #endif  // LIBWEAVE_INCLUDE_WEAVE_EXPORT_H_
diff --git a/include/weave/test/mock_device.h b/include/weave/test/mock_device.h
index 88cc5e0..612afb9 100644
--- a/include/weave/test/mock_device.h
+++ b/include/weave/test/mock_device.h
@@ -24,6 +24,8 @@
   MOCK_METHOD1(AddTraitDefinitionsFromJson, void(const std::string& json));
   MOCK_METHOD1(AddTraitDefinitions, void(const base::DictionaryValue& dict));
   MOCK_CONST_METHOD0(GetTraits, const base::DictionaryValue&());
+  MOCK_METHOD1(AddTraitDefsChangedCallback,
+               void(const base::Closure& callback));
   MOCK_METHOD3(AddComponent, bool(const std::string& name,
                                   const std::vector<std::string>& traits,
                                   ErrorPtr* error));
diff --git a/src/device_manager.cc b/src/device_manager.cc
index e99ca4d..cb575b8 100644
--- a/src/device_manager.cc
+++ b/src/device_manager.cc
@@ -105,6 +105,10 @@
   return component_manager_->GetTraits();
 }
 
+void DeviceManager::AddTraitDefsChangedCallback(const base::Closure& callback) {
+  component_manager_->AddTraitDefChangedCallback(callback);
+}
+
 bool DeviceManager::AddComponent(const std::string& name,
                                  const std::vector<std::string>& traits,
                                  ErrorPtr* error) {
diff --git a/src/device_manager.h b/src/device_manager.h
index bf641e2..d21f398 100644
--- a/src/device_manager.h
+++ b/src/device_manager.h
@@ -39,6 +39,7 @@
   void AddTraitDefinitionsFromJson(const std::string& json) override;
   void AddTraitDefinitions(const base::DictionaryValue& dict) override;
   const base::DictionaryValue& GetTraits() const override;
+  void AddTraitDefsChangedCallback(const base::Closure& callback) override;
   bool AddComponent(const std::string& name,
                     const std::vector<std::string>& traits,
                     ErrorPtr* error) override;