Remove #pragma once from ash

ash/system/tray/system_tray_item.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_TRAY_SYSTEM_TRAY_ITEM_H_
 #define ASH_SYSTEM_TRAY_SYSTEM_TRAY_ITEM_H_
-#pragma once
 
 #include "ash/ash_export.h"
 #include "ash/system/user/login_status.h"
 #include "ash/wm/shelf_types.h"
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 
 namespace views {
 class View;
 }
@@ skipping 76 matching lines @@
   void HideNotificationView();
 
  private:
 
   DISALLOW_COPY_AND_ASSIGN(SystemTrayItem);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_TRAY_SYSTEM_TRAY_ITEM_H_