Remove #pragma once from ash

ash/system/ime/ime_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_SYSTEM_IME_IME_OBSERVER_H_
 #define ASH_SYSTEM_IME_IME_OBSERVER_H_
-#pragma once
 
 namespace ash {
 
 class IMEObserver {
  public:
   virtual ~IMEObserver() {}
 
   // Notify the observer that the IME state has changed, and should be
   // refreshed.  |show_message| indicates whether the user should be alerted of
   // the change.
   virtual void OnIMERefresh(bool show_message) = 0;
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_IME_IME_OBSERVER_H_