[GCM] Adding the OnSendAcknowledgement event

components/gcm_driver/gcm_app_handler.h

 // Copyright (c) 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_GCM_DRIVER_GCM_APP_HANDLER_H_
 #define COMPONENTS_GCM_DRIVER_GCM_APP_HANDLER_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 18 matching lines @@
                          const GCMClient::IncomingMessage& message) = 0;
 
   // Called when some GCM messages have been deleted from the server.
   virtual void OnMessagesDeleted(const std::string& app_id) = 0;
 
   // Called when a GCM message failed to be delivered.
   virtual void OnSendError(
       const std::string& app_id,
       const GCMClient::SendErrorDetails& send_error_details) = 0;
 
+  // Called when a GCM message was received by GCM server.
+  virtual void OnSendAcknowledged(const std::string& app_id,
+                                  const std::string& message_id) = 0;
+
   // Called when a new connection is established and a successful handshake
   // has been performed. Note that |ip_endpoint| is only set if available for
   // the current platform.
   // Default implementation does nothing.
   virtual void OnConnected(const net::IPEndPoint& ip_endpoint);
 
   // Called when the connection is interrupted.
   // Default implementation does nothing.
   virtual void OnDisconnected();
 
   // If no app handler has been added with the exact app_id of an incoming
   // event, all handlers will be asked (in arbitrary order) whether they can
   // handle the app_id, and the first to return true will receive the event.
   virtual bool CanHandle(const std::string& app_id) const;
 };
 
 }  // namespace gcm
 
 #endif  // COMPONENTS_GCM_DRIVER_GCM_APP_HANDLER_H_