diff --git a/buffet/async_event_sequencer.cc b/buffet/async_event_sequencer.cc
new file mode 100644
index 0000000..b447c70
--- /dev/null
+++ b/buffet/async_event_sequencer.cc
@@ -0,0 +1,102 @@
+// Copyright 2014 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "buffet/async_event_sequencer.h"
+
+namespace buffet {
+
+namespace dbus_utils {
+
+AsyncEventSequencer::AsyncEventSequencer() { }
+AsyncEventSequencer::~AsyncEventSequencer() { }
+
+AsyncEventSequencer::Handler AsyncEventSequencer::GetHandler(
+    const std::string& descriptive_message, bool failure_is_fatal) {
+  CHECK(!started_) << "Cannot create handlers after OnAllTasksCompletedCall()";
+  int unique_registration_id = ++registration_counter_;
+  outstanding_registrations_.insert(unique_registration_id);
+  return base::Bind(&AsyncEventSequencer::HandleFinish, this,
+                    unique_registration_id, descriptive_message,
+                    failure_is_fatal);
+}
+
+AsyncEventSequencer::ExportHandler AsyncEventSequencer::GetExportHandler(
+        const std::string& interface_name, const std::string& method_name,
+        const std::string& descriptive_message, bool failure_is_fatal) {
+  auto finish_handler = GetHandler(descriptive_message, failure_is_fatal);
+  return base::Bind(&AsyncEventSequencer::HandleDBusMethodExported, this,
+                    finish_handler,
+                    interface_name,
+                    method_name);
+}
+
+void AsyncEventSequencer::OnAllTasksCompletedCall(
+    std::vector<CompletionAction> actions) {
+  CHECK(!started_) << "OnAllTasksCompletedCall called twice!";
+  started_ = true;
+  completion_actions_.assign(actions.begin(), actions.end());
+  // All of our callbacks might have been called already.
+  PossiblyRunCompletionActions();
+}
+
+void AsyncEventSequencer::HandleFinish(int registration_number,
+                                       const std::string& error_message,
+                                       bool failure_is_fatal, bool success) {
+  RetireRegistration(registration_number);
+  CheckForFailure(failure_is_fatal, success, error_message);
+  PossiblyRunCompletionActions();
+}
+
+void AsyncEventSequencer::HandleDBusMethodExported(
+    const AsyncEventSequencer::Handler& finish_handler,
+    const std::string& expected_interface_name,
+    const std::string& expected_method_name,
+    const std::string& actual_interface_name,
+    const std::string& actual_method_name, bool success) {
+  CHECK(expected_method_name == actual_method_name)
+      << "Exported DBus method '" << actual_method_name << "' "
+      << "but expected '" << expected_method_name << "'";
+  CHECK(expected_interface_name == actual_interface_name)
+      << "Exported method DBus interface '" << actual_interface_name << "' "
+      << "but expected '" << expected_interface_name << "'";
+  finish_handler.Run(success);
+}
+
+
+void AsyncEventSequencer::RetireRegistration(int registration_number) {
+  const size_t handlers_retired = outstanding_registrations_.erase(
+      registration_number);
+  CHECK(handlers_retired == 1)
+      << "Tried to retire invalid handler " << registration_number << ")";
+}
+
+void AsyncEventSequencer::CheckForFailure(bool failure_is_fatal, bool success,
+                                          const std::string& error_message) {
+  if (failure_is_fatal) {
+    CHECK(success) << error_message;
+  }
+  if (!success) {
+    LOG(ERROR) << error_message;
+    had_failures_ = true;
+  }
+}
+
+void AsyncEventSequencer::PossiblyRunCompletionActions() {
+  if (!started_ || !outstanding_registrations_.empty()) {
+    // Don't run completion actions if we have any outstanding
+    // Handlers outstanding or if any more handlers might
+    // be scheduled in the future.
+    return;
+  }
+  for (auto&& completion_action : completion_actions_) {
+    // Should this be put on the message loop or run directly?
+    completion_action.Run(!had_failures_);
+  }
+  // Discard our references to those actions.
+  completion_actions_.clear();
+}
+
+}  // namespace dbus_utils
+
+}  // namespace buffet