chromeos: Move files in //ash/common to //ash, part 1

ash/system/network/network_observer.h

 // Copyright (c) 2012 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 ASH_COMMON_SYSTEM_CHROMEOS_NETWORK_NETWORK_OBSERVER_H_
-#define ASH_COMMON_SYSTEM_CHROMEOS_NETWORK_NETWORK_OBSERVER_H_
+#ifndef ASH_SYSTEM_NETWORK_NETWORK_OBSERVER_H_
+#define ASH_SYSTEM_NETWORK_NETWORK_OBSERVER_H_
 
 namespace ash {
 
 class NetworkObserver {
  public:
   virtual ~NetworkObserver() {}
 
   // Called to request toggling Wi-Fi enable/disable, e.g. from an accelerator.
   // NOTE: Toggling is asynchronous and subsequent calls to query the current
   // state may return the old value.
   virtual void RequestToggleWifi() = 0;
 };
 
 }  // namespace ash
 
-#endif  // ASH_COMMON_SYSTEM_CHROMEOS_NETWORK_NETWORK_OBSERVER_H_
+#endif  // ASH_SYSTEM_NETWORK_NETWORK_OBSERVER_H_