Create video and audio decoder threads on demand.

media/filters/ffmpeg_video_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_VIDEO_DECODER_H_
 #define MEDIA_FILTERS_FFMPEG_VIDEO_DECODER_H_
 
 #include <deque>
 
+#include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "media/base/filters.h"
 #include "media/crypto/aes_decryptor.h"
 #include "ui/gfx/size.h"
 
 class MessageLoop;
 
 struct AVCodecContext;
 struct AVFrame;
 
 namespace media {
 
 class MEDIA_EXPORT FFmpegVideoDecoder : public VideoDecoder {
  public:
-  explicit FFmpegVideoDecoder(MessageLoop* message_loop);
+  FFmpegVideoDecoder(const base::Callback<MessageLoop*()>& message_loop_cb);
   virtual ~FFmpegVideoDecoder();
 
   // Filter implementation.
   virtual void Stop(const base::Closure& callback) OVERRIDE;
   virtual void Seek(base::TimeDelta time, const FilterStatusCB& cb) OVERRIDE;
   virtual void Pause(const base::Closure& callback) OVERRIDE;
   virtual void Flush(const base::Closure& callback) OVERRIDE;
 
   // VideoDecoder implementation.
   virtual void Initialize(DemuxerStream* demuxer_stream,
@@ skipping 26 matching lines @@
   void DeliverFrame(const scoped_refptr<VideoFrame>& video_frame);
 
   // Releases resources associated with |codec_context_| and |av_frame_|
   // and resets them to NULL.
   void ReleaseFFmpegResources();
 
   // Allocates a video frame based on the current format and dimensions based on
   // the current state of |codec_context_|.
   scoped_refptr<VideoFrame> AllocateVideoFrame();
 
+  // This is !is_null() iff Initialize() hasn't been called.
+  base::Callback<MessageLoop*()> message_loop_factory_cb_;
+
   MessageLoop* message_loop_;
 
   DecoderState state_;
 
   StatisticsCB statistics_cb_;
 
   ReadCB read_cb_;
 
   // FFmpeg structures owned by this object.
   AVCodecContext* codec_context_;
@@ skipping 11 matching lines @@
   scoped_refptr<DemuxerStream> demuxer_stream_;
 
   AesDecryptor decryptor_;
 
   DISALLOW_COPY_AND_ASSIGN(FFmpegVideoDecoder);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_FFMPEG_VIDEO_DECODER_H_