Remove #pragma once from ash

ash/drag_drop/drag_image_view.h

 // Copyright (c) 2011 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_DRAG_DROP_DRAG_IMAGE_VIEW_H_
 #define ASH_DRAG_DROP_DRAG_IMAGE_VIEW_H_
-#pragma once
 
 #include "ui/views/controls/image_view.h"
 
 namespace views {
 class Widget;
 }
 
 namespace ash {
 namespace internal {
 
@@ skipping 14 matching lines @@
  private:
   scoped_ptr<views::Widget> widget_;
 
   DISALLOW_COPY_AND_ASSIGN(DragImageView);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_DRAG_DROP_DRAG_IMAGE_VIEW_H_