Simplify VideoDecodeEngine interface by making everything synchronous.

media/video/ffmpeg_video_decode_engine.h

Index: media/video/ffmpeg_video_decode_engine.h
diff --git a/media/video/ffmpeg_video_decode_engine.h b/media/video/ffmpeg_video_decode_engine.h
index 3ac74118056ffe743d0b371290fe01bd344a0b30..7c94017f3980e58699331916ded15ef5b907dae1 100644
--- a/media/video/ffmpeg_video_decode_engine.h
+++ b/media/video/ffmpeg_video_decode_engine.h
@@ -5,13 +5,9 @@
 #ifndef MEDIA_VIDEO_FFMPEG_VIDEO_DECODE_ENGINE_H_
 #define MEDIA_VIDEO_FFMPEG_VIDEO_DECODE_ENGINE_H_
 
-#include <deque>
-
-#include "base/memory/scoped_ptr.h"
-#include "media/ffmpeg/ffmpeg_common.h"
+#include "base/compiler_specific.h"
 #include "media/video/video_decode_engine.h"
 
-// FFmpeg types.
 struct AVCodecContext;
 struct AVFrame;
 
@@ -22,47 +18,24 @@ class MEDIA_EXPORT FFmpegVideoDecodeEngine : public VideoDecodeEngine {
   FFmpegVideoDecodeEngine();
   virtual ~FFmpegVideoDecodeEngine();
 
-  // Implementation of the VideoDecodeEngine Interface.
-  virtual void Initialize(VideoDecodeEngine::EventHandler* event_handler,
-                          const VideoDecoderConfig& config);
-  virtual void ConsumeVideoSample(scoped_refptr<Buffer> buffer);
-  virtual void ProduceVideoFrame(scoped_refptr<VideoFrame> frame);
-  virtual void Uninitialize();
-  virtual void Flush();
-  virtual void Seek();
+  // VideoDecodeEngine implementation.
+  virtual bool Initialize(const VideoDecoderConfig& config) OVERRIDE;
+  virtual void Uninitialize() OVERRIDE;
+  virtual bool Decode(scoped_refptr<Buffer> buffer,
+                      scoped_refptr<VideoFrame>* video_frame) OVERRIDE;
+  virtual void Flush() OVERRIDE;
 
  private:
-  void DecodeFrame(scoped_refptr<Buffer> buffer);
-  void ReadInput();
-  void TryToFinishPendingFlush();
+  // Reallocates the video frame if format or dimensions differ.

[Ami GONE FROM CHROMIUM, 2011/11/01 22:17:40]

I think "differ" here refers to a mismatch between *video_frame and *av_frame. 
Can you clarify the comment and function name?
(if it's doing what I think it is then maybe AlignToAVFrame()?)

[scherkus (not reviewing), 2011/11/03 04:55:59]

since we're no longer attempting to do buffer recycling in this CL we actually
are always allocating -- will update function name and docs

+  void ReallocateVideoFrameIfNecessary(scoped_refptr<VideoFrame>* video_frame);
 
   AVCodecContext* codec_context_;

[Ami GONE FROM CHROMIUM, 2011/11/01 22:17:40]

Add ownership comments?

[scherkus (not reviewing), 2011/11/03 04:55:59]

Done.

-  scoped_ptr_malloc<AVFrame, ScopedPtrAVFree> av_frame_;
-  VideoDecodeEngine::EventHandler* event_handler_;
+  AVFrame* av_frame_;
 
   // Frame rate of the video.
   int frame_rate_numerator_;
   int frame_rate_denominator_;
 
-  // Indicate how many buffers are pending on input port of this filter:
-  // Increment when engine receive one input packet from demuxer;
-  // Decrement when engine send one input packet to demuxer;
-  int pending_input_buffers_;
-
-  // Indicate how many buffers are pending on output port of this filter:
-  // Increment when engine receive one output frame from renderer;
-  // Decrement when engine send one output frame to renderer;
-  int pending_output_buffers_;
-
-  // Whether end of stream had been reached at output side.
-  bool output_eos_reached_;
-
-  // Used when direct rendering is disabled to hold available output buffers.
-  std::deque<scoped_refptr<VideoFrame> > frame_queue_available_;
-
-  // Whether flush operation is pending.
-  bool flush_pending_;
-
   DISALLOW_COPY_AND_ASSIGN(FFmpegVideoDecodeEngine);
 };