Remove #pragma once from content

content/browser/system_message_window_win.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 CONTENT_BROWSER_SYSTEM_MESSAGE_WINDOW_WIN_H_
 #define CONTENT_BROWSER_SYSTEM_MESSAGE_WINDOW_WIN_H_
-#pragma once
 
 #include <windows.h>
 
 #include "base/basictypes.h"
 #include "content/common/content_export.h"
 
 class CONTENT_EXPORT SystemMessageWindowWin {
  public:
   SystemMessageWindowWin();
 
@@ skipping 18 matching lines @@
     return ::DefWindowProc(hwnd, message, wparam, lparam);
   }
 
   HMODULE instance_;
   HWND window_;
 
   DISALLOW_COPY_AND_ASSIGN(SystemMessageWindowWin);
 };
 
 #endif  // CONTENT_BROWSER_SYSTEM_MESSAGE_WINDOW_WIN_H_