Remove #pragma once from content

content/common/media/audio_param_traits.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_COMMON_MEDIA_AUDIO_AUDIO_PARAM_TRAITS_H_
 #define CONTENT_COMMON_MEDIA_AUDIO_AUDIO_PARAM_TRAITS_H_
-#pragma once
 
 #include "ipc/ipc_message.h"
 #include "ipc/ipc_param_traits.h"
 
 namespace media {
 class AudioParameters;
 }
 
 namespace IPC {
 
 template <>
 struct ParamTraits<media::AudioParameters> {
   typedef media::AudioParameters param_type;
   static void Write(Message* m, const param_type& p);
   static bool Read(const Message* m, PickleIterator* iter, param_type* r);
   static void Log(const param_type& p, std::string* l);
 };
 
 } // namespace IPC
 
 #endif  // CONTENT_COMMON_MEDIA_AUDIO_AUDIO_PARAM_TRAITS_H_