Use enum instead of string in MessageLoopFactory::GetMessageLoop*

media/filters/ffmpeg_audio_decoder.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 MEDIA_FILTERS_FFMPEG_AUDIO_DECODER_H_
 #define MEDIA_FILTERS_FFMPEG_AUDIO_DECODER_H_
 
 #include <list>
 
 #include "base/callback.h"
-#include "base/message_loop.h"
 #include "media/base/audio_decoder.h"
 #include "media/base/demuxer_stream.h"
 
 struct AVCodecContext;
 struct AVFrame;
 
+namespace base {
+class MessageLoopProxy;
+}
+
 namespace media {
 
 class DataBuffer;
 class DecoderBuffer;
 
 class MEDIA_EXPORT FFmpegAudioDecoder : public AudioDecoder {
  public:
-  FFmpegAudioDecoder(const base::Callback<MessageLoop*()>& message_loop_cb);
+  typedef base::Callback<
+      scoped_refptr<base::MessageLoopProxy>()> MessageLoopFactoryCB;
+  explicit FFmpegAudioDecoder(
+      const MessageLoopFactoryCB& message_loop_factory_cb);
 
   // AudioDecoder implementation.
   virtual void Initialize(const scoped_refptr<DemuxerStream>& stream,
                           const PipelineStatusCB& status_cb,
                           const StatisticsCB& statistics_cb) OVERRIDE;
   virtual void Read(const ReadCB& read_cb) OVERRIDE;
   virtual int bits_per_channel() OVERRIDE;
   virtual ChannelLayout channel_layout() OVERRIDE;
   virtual int samples_per_second() OVERRIDE;
   virtual void Reset(const base::Closure& closure) OVERRIDE;
@@ skipping 15 matching lines @@
   void ReadFromDemuxerStream();
   void DecodeBuffer(DemuxerStream::Status status,
                     const scoped_refptr<DecoderBuffer>& buffer);
 
   // Returns the timestamp that should be used for the next buffer returned
   // via |read_cb_|. It is calculated from |output_timestamp_base_| and
   // |total_frames_decoded_|.
   base::TimeDelta GetNextOutputTimestamp() const;
 
   // This is !is_null() iff Initialize() hasn't been called.
-  base::Callback<MessageLoop*()> message_loop_factory_cb_;
-  MessageLoop* message_loop_;
+  MessageLoopFactoryCB message_loop_factory_cb_;
+
+  scoped_refptr<base::MessageLoopProxy> message_loop_;
 
   scoped_refptr<DemuxerStream> demuxer_stream_;
   StatisticsCB statistics_cb_;
   AVCodecContext* codec_context_;
 
   // Decoded audio format.
   int bits_per_channel_;
   ChannelLayout channel_layout_;
   int samples_per_second_;
 
@@ skipping 11 matching lines @@
   AVFrame* av_frame_;
 
   ReadCB read_cb_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(FFmpegAudioDecoder);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_FFMPEG_AUDIO_DECODER_H_