Provide a mechanism for the GCM driver to send message receipts to GCM.

components/gcm_driver/gcm_driver_desktop.cc

Index: components/gcm_driver/gcm_driver_desktop.cc
diff --git a/components/gcm_driver/gcm_driver_desktop.cc b/components/gcm_driver/gcm_driver_desktop.cc
index 599957d2a5979fced996c2440031f4cee4344b7c..6408981e2b7d179d1df6d263fd5a0a03fff330a8 100644
--- a/components/gcm_driver/gcm_driver_desktop.cc
+++ b/components/gcm_driver/gcm_driver_desktop.cc
@@ -55,6 +55,9 @@ class GCMDriverDesktop::IOWorker : public GCMClient::Delegate {
                       GCMClient::Result result) override;
   void OnMessageReceived(const std::string& app_id,
                          const IncomingMessage& message) override;
+  void OnMessageReceivedError(const std::string& app_id,
+                              const std::string& message_id,
+                              int status) override;
   void OnMessagesDeleted(const std::string& app_id) override;
   void OnMessageSendError(
       const std::string& app_id,
@@ -244,6 +247,17 @@ void GCMDriverDesktop::IOWorker::OnMessageReceived(
                  message));
 }
 
+void GCMDriverDesktop::IOWorker::OnMessageReceivedError(
+    const std::string& app_id,
+    const std::string& message_id,
+    int status) {
+  DCHECK(io_thread_->RunsTasksOnCurrentThread());
+
+  ui_thread_->PostTask(
+      FROM_HERE, base::Bind(&GCMDriverDesktop::MessageReceivedError, service_,
+                            app_id, message_id, status));
+}
+
 void GCMDriverDesktop::IOWorker::OnMessagesDeleted(const std::string& app_id) {
   DCHECK(io_thread_->RunsTasksOnCurrentThread());
 
@@ -1226,6 +1240,18 @@ void GCMDriverDesktop::MessageReceived(const std::string& app_id,
   DispatchMessage(app_id, message);
 }
 
+void GCMDriverDesktop::MessageReceivedError(const std::string& app_id,
+                                            const std::string& message_id,
+                                            int status) {
+  DCHECK(ui_thread_->RunsTasksOnCurrentThread());
+
+  // Drop the event if the service has been stopped.
+  if (!gcm_started_)
+    return;
+
+  SendMessageReceipt(app_id, message_id, status);
+}
+
 void GCMDriverDesktop::MessagesDeleted(const std::string& app_id) {
   DCHECK(ui_thread_->RunsTasksOnCurrentThread());