[GCM] Adding the OnSendAcknowledgement event

components/gcm_driver/fake_gcm_client.h

 // Copyright 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_FAKE_GCM_CLIENT_H_
 #define COMPONENTS_GCM_DRIVER_FAKE_GCM_CLIENT_H_
 
 #include "base/compiler_specific.h"
 #include "base/memory/weak_ptr.h"
 #include "components/gcm_driver/gcm_client.h"
@@ skipping 69 matching lines @@
   void CheckinFinished();
   void RegisterFinished(const std::string& app_id,
                         const std::string& registrion_id);
   void UnregisterFinished(const std::string& app_id);
   void SendFinished(const std::string& app_id, const OutgoingMessage& message);
   void MessageReceived(const std::string& app_id,
                        const IncomingMessage& message);
   void MessagesDeleted(const std::string& app_id);
   void MessageSendError(const std::string& app_id,
                         const SendErrorDetails& send_error_details);
+  void SendAcknowledgement(const std::string& app_id,
+                           const std::string& message_id);
 
   Delegate* delegate_;
   Status status_;
   StartMode start_mode_;
   scoped_refptr<base::SequencedTaskRunner> ui_thread_;
   scoped_refptr<base::SequencedTaskRunner> io_thread_;
   base::WeakPtrFactory<FakeGCMClient> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(FakeGCMClient);
 };
 
 }  // namespace gcm
 
 #endif  // COMPONENTS_GCM_DRIVER_FAKE_GCM_CLIENT_H_