Add DefaultNetworkChanged signal for ConnectivityStateHelper observers

chrome/browser/chromeos/net/connectivity_state_helper_observer.h

 // Copyright (c) 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 CHROME_BROWSER_CHROMEOS_NET_CONNECTIVITY_STATE_HELPER_OBSERVER_H_
 #define CHROME_BROWSER_CHROMEOS_NET_CONNECTIVITY_STATE_HELPER_OBSERVER_H_
 
 namespace chromeos {
 
 // A common observer interface used by the ConnectivityStateHelper object to
 // relay observing events received from the (older) NetworkLibrary or the (new)
 // NetworkStateHandler implementations.
 class ConnectivityStateHelperObserver {
  public:
   // Called when there's a change on the connection manager.
   virtual void NetworkManagerChanged() = 0;
+
+  // Called when the default network changes.
+  virtual void DefaultNetworkChanged() = 0;
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_NET_CONNECTIVITY_STATE_HELPER_OBSERVER_H_