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

components/gcm_driver/gcm_driver_desktop.h

Index: components/gcm_driver/gcm_driver_desktop.h
diff --git a/components/gcm_driver/gcm_driver_desktop.h b/components/gcm_driver/gcm_driver_desktop.h
index cdd0ac79a685c8064adf84eb63b25a56367ee674..937b1780d866a9337a6feac2ee6ccc1eea0d29d0 100644
--- a/components/gcm_driver/gcm_driver_desktop.h
+++ b/components/gcm_driver/gcm_driver_desktop.h
@@ -157,7 +157,8 @@ class GCMDriverDesktop : public GCMDriver,
 
   // Callbacks posted from IO thread to UI thread.
   void MessageReceived(const std::string& app_id,
-                       const IncomingMessage& message);
+                       const IncomingMessage& message,
+                       const MessageReceiptCallback& receipt_callback);
   void MessagesDeleted(const std::string& app_id);
   void MessageSendError(const std::string& app_id,
                         const GCMClient::SendErrorDetails& send_error_details);
@@ -183,6 +184,9 @@ class GCMDriverDesktop : public GCMDriver,
                            const std::string& scope,
                            GCMClient::Result result);
 
+  void DoSendMessageReceipt(const MessageReceiptCallback& receipt_callback,
+                            GCMMessageStatus status);

[Peter Beverloo, 2017/02/13 13:47:07]

Please add this around line 157.

[harkness, 2017/02/14 19:22:29]

Done.

+
   std::unique_ptr<GCMChannelStatusSyncer> gcm_channel_status_syncer_;
 
   // Flag to indicate whether the user is signed in to a GAIA account.