[GCM] Add support for canary connection attempts

google_apis/gcm/engine/connection_factory.h

 // Copyright 2013 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 GOOGLE_APIS_GCM_ENGINE_CONNECTION_FACTORY_H_
 #define GOOGLE_APIS_GCM_ENGINE_CONNECTION_FACTORY_H_
 
 #include "base/time/time.h"
 #include "google_apis/gcm/base/gcm_export.h"
 #include "google_apis/gcm/engine/connection_handler.h"
@@ skipping 12 matching lines @@
   typedef base::Callback<void(mcs_proto::LoginRequest* login_request)>
       BuildLoginRequestCallback;
 
   // Reasons for triggering a connection reset. Note that these enums are
   // consumed by a histogram, so ordering should not be modified.
   enum ConnectionResetReason {
     LOGIN_FAILURE,      // Login response included an error.
     CLOSE_COMMAND,      // Received a close command.
     HEARTBEAT_FAILURE,  // Heartbeat was not acknowledged in time.
     SOCKET_FAILURE,     // net::Socket error.
+    NETWORK_CHANGE,     // NetworkChangeNotifier notified of a network change.
     // Count of total number of connection reset reasons. All new reset reasons
     // should be added above this line.
     CONNECTION_RESET_COUNT,
   };
 
   ConnectionFactory();
   virtual ~ConnectionFactory();
 
   // Initialize the factory, creating a connection handler with a disconnected
   // socket. Should only be called once.
@@ skipping 30 matching lines @@
   // Manually reset the connection. This can occur if an application specific
   // event forced a reset (e.g. server sends a close connection response).
   // If the last connection was made within kConnectionResetWindowSecs, the old
   // backoff is restored, else a new backoff kicks off.
   virtual void SignalConnectionReset(ConnectionResetReason reason) = 0;
 };
 
 }  // namespace gcm
 
 #endif  // GOOGLE_APIS_GCM_ENGINE_CONNECTION_FACTORY_H_