Remove #pragma once from ash

ash/launcher/launcher_icon_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_LAUNCHER_LAUNCHER_ICON_OBSERVER_H_
 #define ASH_LAUNCHER_LAUNCHER_ICON_OBSERVER_H_
-#pragma once
 
 #include "ash/ash_export.h"
 #include "base/basictypes.h"
 
 namespace ash {
 
 class ASH_EXPORT LauncherIconObserver {
  public:
   // Invoked when any icon on launcher changes position.
   virtual void OnLauncherIconPositionsChanged() = 0;
 
  protected:
   virtual ~LauncherIconObserver() {}
 };
 
 }  // namespace ash
 
 #endif  // ASH_LAUNCHER_LAUNCHER_ICON_OBSERVER_H_