[GCM] Adding the OnSendAcknowledgement event

components/gcm_driver/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_GCM_CLIENT_H_
 #define COMPONENTS_GCM_DRIVER_GCM_CLIENT_H_
 
 #include <map>
 #include <string>
 #include <vector>
@@ skipping 166 matching lines @@
     // |app_id|: application ID.
     virtual void OnMessagesDeleted(const std::string& app_id) = 0;
 
     // Called when a message failed to send to the server.
     // |app_id|: application ID.
     // |send_error_detials|: Details of the send error event, like mesasge ID.
     virtual void OnMessageSendError(
         const std::string& app_id,
         const SendErrorDetails& send_error_details) = 0;
 
+    // Called when a message was acknowledged by the GCM server.
+    // |app_id|: application ID.
+    // |message_id|: ID of the acknowledged message.
+    virtual void OnSendAcknowledged(const std::string& app_id,
+                                    const std::string& message_id) = 0;
+
     // Called when the GCM becomes ready. To get to this state, GCMClient
     // finished loading from the GCM store and retrieved the device check-in
     // from the server if it hadn't yet.
     virtual void OnGCMReady() = 0;
 
     // Called when activities are being recorded and a new activity has just
     // been recorded.
     virtual void OnActivityRecorded() = 0;
 
     // Called when a new connection is established and a successful handshake
@@ skipping 71 matching lines @@
 
   // Sets a list of accounts with OAuth2 tokens for the next checkin.
   // |account_tokens| maps email addresses to OAuth2 access tokens.
   virtual void SetAccountsForCheckin(
       const std::map<std::string, std::string>& account_tokens) = 0;
 };
 
 }  // namespace gcm
 
 #endif  // COMPONENTS_GCM_DRIVER_GCM_CLIENT_H_