Use enum instead of string in MessageLoopFactory::GetMessageLoop*

media/filters/ffmpeg_demuxer.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.
 
 // Implements the Demuxer interface using FFmpeg's libavformat.  At this time
 // will support demuxing any audio/video format thrown at it.  The streams
 // output mime types audio/x-ffmpeg and video/x-ffmpeg and include an integer
 // key FFmpegCodecID which contains the CodecID enumeration value.  The CodecIDs
 // can be used to create and initialize the corresponding FFmpeg decoder.
 //
@@ skipping 122 matching lines @@
   // already been demuxed without having the demuxer thread sending the
   // buffers. |lock_| must be acquired before any access to |buffer_queue_|,
   // |read_queue_|, or |stopped_|.
   mutable base::Lock lock_;
 
   DISALLOW_COPY_AND_ASSIGN(FFmpegDemuxerStream);
 };
 
 class MEDIA_EXPORT FFmpegDemuxer : public Demuxer, public FFmpegURLProtocol {
  public:
-  FFmpegDemuxer(MessageLoop* message_loop,
+  FFmpegDemuxer(const scoped_refptr<base::MessageLoopProxy>& message_loop,
                 const scoped_refptr<DataSource>& data_source);
 
   // Posts a task to perform additional demuxing.
   virtual void PostDemuxTask();
 
   // Demuxer implementation.
   virtual void Initialize(DemuxerHost* host,
                           const PipelineStatusCB& status_cb) OVERRIDE;
   virtual void Stop(const base::Closure& callback) OVERRIDE;
   virtual void Seek(base::TimeDelta time, const PipelineStatusCB& cb) OVERRIDE;
   virtual void OnAudioRendererDisabled() OVERRIDE;
   virtual void SetPlaybackRate(float playback_rate) OVERRIDE;
   virtual scoped_refptr<DemuxerStream> GetStream(
       DemuxerStream::Type type) OVERRIDE;
   virtual base::TimeDelta GetStartTime() const OVERRIDE;
 
   // FFmpegURLProtocol implementation.
   virtual size_t Read(size_t size, uint8* data) OVERRIDE;
   virtual bool GetPosition(int64* position_out) OVERRIDE;
   virtual bool SetPosition(int64 position) OVERRIDE;
   virtual bool GetSize(int64* size_out) OVERRIDE;
   virtual bool IsStreaming() OVERRIDE;
 
   // Provide access to FFmpegDemuxerStream.
-  MessageLoop* message_loop();
+  scoped_refptr<base::MessageLoopProxy> message_loop();
 
   // Allow FFmpegDemuxerStream to notify us when there is updated information
   // about what buffered data is available.
   void NotifyBufferingChanged();
 
  private:
   // To allow tests access to privates.
   friend class FFmpegDemuxerTest;
 
   virtual ~FFmpegDemuxer();
@@ skipping 32 matching lines @@
   // read or kReadError in case of error.
   virtual void SignalReadCompleted(int size);
 
   // Returns the stream from |streams_| that matches |type| as an
   // FFmpegDemuxerStream.
   scoped_refptr<FFmpegDemuxerStream> GetFFmpegStream(
       DemuxerStream::Type type) const;
 
   DemuxerHost* host_;
 
-  MessageLoop* message_loop_;
+  scoped_refptr<base::MessageLoopProxy> message_loop_;
 
   // FFmpeg context handle.
   AVFormatContext* format_context_;
 
   // |streams_| mirrors the AVStream array in |format_context_|. It contains
   // FFmpegDemuxerStreams encapsluating AVStream objects at the same index.
   //
   // Since we only support a single audio and video stream, |streams_| will
   // contain NULL entries for additional audio/video streams as well as for
   // stream types that we do not currently support.
@@ skipping 34 matching lines @@
   // Set if we know duration of the audio stream. Used when processing end of
   // stream -- at this moment we definitely know duration.
   bool duration_known_;
 
   DISALLOW_COPY_AND_ASSIGN(FFmpegDemuxer);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_FFMPEG_DEMUXER_H_