Remove #pragma once from ash

ash/system/network/sms_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_SYSTEM_NETWORK_SMS_OBSERVER_H
 #define ASH_SYSTEM_NETWORK_SMS_OBSERVER_H
-#pragma once
 
 #include "base/string16.h"
 
 namespace base {
 class DictionaryValue;
 }
 
 namespace ash {
 
 const char kSmsNumberKey[] = "number";
 const char kSmsTextKey[] = "text";
 
 class SmsObserver {
  public:
   virtual ~SmsObserver() {}
 
   virtual void AddMessage(const base::DictionaryValue& message) = 0;
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_NETWORK_SMS_OBSERVER_H