[GCM] Extracting GCMConnectionObserver from GCMAppHandler

components/gcm_driver/gcm_connection_observer.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_CONNECTION_OBSERVER_H_
+#define COMPONENTS_GCM_DRIVER_GCM_CONNECTION_OBSERVER_H_
+
+#include "base/basictypes.h"
+
+namespace net {
+class IPEndPoint;
+}
+
+namespace gcm {
+
+// Interface for objects observing GCM connection events.
+class GCMConnectionObserver {
+ public:
+  GCMConnectionObserver();
+  virtual ~GCMConnectionObserver();
+
+  // 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();
+};
+
+}  // namespace gcm
+
+#endif  // COMPONENTS_GCM_DRIVER_GCM_CONNECTION_OBSERVER_H_