Remove #pragma once from ash

ash/wm/system_modal_container_layout_manager.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_WM_SYSTEM_MODAL_CONTAINER_LAYOUT_MANAGER_H_
 #define ASH_WM_SYSTEM_MODAL_CONTAINER_LAYOUT_MANAGER_H_
-#pragma once
 
 #include <vector>
 
 #include "ash/wm/system_modal_container_event_filter_delegate.h"
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 #include "ui/aura/layout_manager.h"
 #include "ui/aura/window_observer.h"
 #include "ash/ash_export.h"
@@ skipping 66 matching lines @@
   // added, and removed when the last is closed.
   scoped_ptr<aura::EventFilter> modality_filter_;
 
   DISALLOW_COPY_AND_ASSIGN(SystemModalContainerLayoutManager);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_WM_SYSTEM_MODAL_CONTAINER_LAYOUT_MANAGER_H_