Remove #pragma once from ash

ash/system/locale/locale_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_LOCALE_LOCALE_OBSERVER_H_
 #define ASH_SYSTEM_LOCALE_LOCALE_OBSERVER_H_
-#pragma once
 
 #include "ash/ash_export.h"
 
 namespace ash {
 
 class ASH_EXPORT LocaleObserver {
  public:
   class Delegate {
    public:
     virtual ~Delegate() {}
 
     virtual void AcceptLocaleChange() = 0;
     virtual void RevertLocaleChange() = 0;
   };
 
   virtual ~LocaleObserver() {}
 
   virtual void OnLocaleChanged(Delegate* delegate,
                                const std::string& cur_locale,
                                const std::string& from_locale,
                                const std::string& to_locale) = 0;
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_LOCALE_LOCALE_OBSERVER_H_