Add a unified observer to replace NetworkManagerObserver

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;
+};
+
+}  // namespace chromeos
+
+#endif  // CHROME_BROWSER_CHROMEOS_NET_CONNECTIVITY_STATE_HELPER_OBSERVER_H_