Remove #pragma once from ash

ash/system/network/tray_network.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_NETWORK_TRAY_NETWORK_H
 #define ASH_SYSTEM_NETWORK_TRAY_NETWORK_H
-#pragma once
 
 #include "ash/system/network/network_observer.h"
 #include "ash/system/tray/system_tray_item.h"
 #include "base/memory/scoped_ptr.h"
 
 namespace ash {
 namespace internal {
 
 namespace tray {
 class NetworkDefaultView;
@@ skipping 45 matching lines @@
   tray::NetworkNotificationView* notification_;
   scoped_ptr<tray::NetworkErrors> errors_;
 
   DISALLOW_COPY_AND_ASSIGN(TrayNetwork);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_NETWORK_TRAY_NETWORK_H