Remove #pragma once from ash

ash/launcher/launcher_model_observer.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_LAUNCHER_LAUNCHER_MODEL_OBSERVER_H_
 #define ASH_LAUNCHER_LAUNCHER_MODEL_OBSERVER_H_
-#pragma once
 
 #include "ash/ash_export.h"
 #include "ash/launcher/launcher_types.h"
 
 namespace ash {
 
 struct LauncherItem;
 
 class ASH_EXPORT LauncherModelObserver {
  public:
@@ skipping 12 matching lines @@
   // before the change.
   virtual void LauncherItemChanged(int index, const LauncherItem& old_item) = 0;
 
  protected:
   virtual ~LauncherModelObserver() {}
 };
 
 }  // namespace ash
 
 #endif  // ASH_LAUNCHER_LAUNCHER_MODEL_OBSERVER_H_