Remove #pragma once from ash

ash/system/tray/tray_notification_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_NOTIFICATION_VIEW_H_
 #define ASH_SYSTEM_TRAY_TRAY_NOTIFICATION_VIEWS_H_
-#pragma once
 
 #include "ui/views/controls/button/image_button.h"
 #include "ui/views/view.h"
 
 namespace gfx {
 class ImageSkia;
 }
 
 namespace views {
 class ImageView;
@@ skipping 56 matching lines @@
   int icon_id_;
   views::ImageView* icon_;
 
   DISALLOW_COPY_AND_ASSIGN(TrayNotificationView);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_TRAY_TRAY_NOTIFICATION_VIEWS_H_