Remove #pragma once from ash

ash/system/tray/tray_item_view.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_TRAY_ITEM_VIEW_H_
 #define ASH_SYSTEM_TRAY_TRAY_ITEM_VIEW_H_
-#pragma once
 
 #include "ui/base/animation/animation_delegate.h"
 #include "ui/views/view.h"
 
 namespace ui {
 class SlideAnimation;
 }
 
 namespace views {
 class ImageView;
@@ skipping 50 matching lines @@
   views::Label* label_;
   views::ImageView* image_view_;
 
   DISALLOW_COPY_AND_ASSIGN(TrayItemView);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_TRAY_TRAY_ITEM_VIEW_H_