Remove #pragma once from ash

ash/key_rewriter_delegate.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_KEY_REWRITER_DELEGATE_H_
 #define ASH_KEY_REWRITER_DELEGATE_H_
-#pragma once
 
 namespace aura {
 class KeyEvent;
 }  // namespace aura
 
 namespace ash {
 
 // Delegate for rewriting or filtering a key event.
 class KeyRewriterDelegate {
  public:
   enum Action {
     ACTION_REWRITE_EVENT,
     ACTION_DROP_EVENT,
   };
 
   virtual ~KeyRewriterDelegate() {}
 
   // A derived class can do either of the following:
   // 1) Just return ACTION_DROP_EVENT to drop the |event|.
   // 2) Rewrite the |event| and return ACTION_REWRITE_EVENT.
   virtual Action RewriteOrFilterKeyEvent(aura::KeyEvent* event) = 0;
 };
 
 }  // namespace ash
 
 #endif  // ASH_KEY_REWRITER_DELEGATE_H_