Simplify VideoDecodeEngine interface by making everything synchronous.

content/renderer/media/capture_video_decoder.h

Index: content/renderer/media/capture_video_decoder.h
diff --git a/content/renderer/media/capture_video_decoder.h b/content/renderer/media/capture_video_decoder.h
index 0c874abf8e4df3059bf8c0efa84304216be41b83..f3e79bed680aefc5b4172ccbfb04682bbef51cda 100644
--- a/content/renderer/media/capture_video_decoder.h
+++ b/content/renderer/media/capture_video_decoder.h
@@ -44,9 +44,8 @@ class CONTENT_EXPORT CaptureVideoDecoder
       media::DemuxerStream* demuxer_stream,
       const base::Closure& filter_callback,
       const media::StatisticsCallback& stat_callback) OVERRIDE;
-  virtual void ProduceVideoFrame(
-      scoped_refptr<media::VideoFrame> video_frame) OVERRIDE;
-  virtual gfx::Size natural_size() OVERRIDE;
+  virtual void Read(const ReadCB& callback) OVERRIDE;
+  virtual const gfx::Size& natural_size() OVERRIDE;
 
   // VideoCapture::EventHandler implementation.
   virtual void OnStarted(media::VideoCapture* capture) OVERRIDE;
@@ -67,7 +66,6 @@ class CONTENT_EXPORT CaptureVideoDecoder
   enum DecoderState {
     kUnInitialized,
     kNormal,
-    kSeeking,
     kStopped,
     kPaused
   };
@@ -82,19 +80,22 @@ class CONTENT_EXPORT CaptureVideoDecoder
       media::DemuxerStream* demuxer_stream,
       const base::Closure& filter_callback,
       const media::StatisticsCallback& stat_callback);
-  void ProduceVideoFrameOnDecoderThread(
-      scoped_refptr<media::VideoFrame> video_frame);
+  void ReadOnDecoderThread(const ReadCB& callback);
 
   void OnStoppedOnDecoderThread(media::VideoCapture* capture);
   void OnBufferReadyOnDecoderThread(
       media::VideoCapture* capture,
       scoped_refptr<media::VideoCapture::VideoFrameBuffer> buf);
 
+  // Delivers the frame to |read_cb_| and resets the callback.
+  void DeliverFrame(const scoped_refptr<media::VideoFrame>& video_frame);
+
   scoped_refptr<base::MessageLoopProxy> message_loop_proxy_;
   scoped_refptr<VideoCaptureImplManager> vc_manager_;
   media::VideoCapture::VideoCaptureCapability capability_;
+  gfx::Size natural_size_;
   DecoderState state_;
-  std::deque<scoped_refptr<media::VideoFrame> > available_frames_;
+  ReadCB read_cb_;
   base::Closure pending_stop_cb_;
   media::StatisticsCallback statistics_callback_;