Simplify VideoDecodeEngine interface by making everything synchronous.

media/filters/ffmpeg_video_decoder.h

Index: media/filters/ffmpeg_video_decoder.h
diff --git a/media/filters/ffmpeg_video_decoder.h b/media/filters/ffmpeg_video_decoder.h
index ef4797704580b72a0309981e15819db94602c36d..5b40699e1edde089956e7a55fbad331c1f13b75e 100644
--- a/media/filters/ffmpeg_video_decoder.h
+++ b/media/filters/ffmpeg_video_decoder.h
@@ -7,9 +7,9 @@
 
 #include <deque>
 
+#include "base/memory/scoped_ptr.h"
 #include "media/base/filters.h"
 #include "media/base/pts_stream.h"
-#include "media/video/video_decode_engine.h"
 #include "ui/gfx/size.h"
 
 class MessageLoop;
@@ -18,9 +18,7 @@ namespace media {
 
 class VideoDecodeEngine;
 
-class MEDIA_EXPORT FFmpegVideoDecoder
-    : public VideoDecoder,
-      public VideoDecodeEngine::EventHandler {
+class MEDIA_EXPORT FFmpegVideoDecoder : public VideoDecoder {
  public:
   explicit FFmpegVideoDecoder(MessageLoop* message_loop);
   virtual ~FFmpegVideoDecoder();
@@ -35,62 +33,42 @@ class MEDIA_EXPORT FFmpegVideoDecoder
   virtual void Initialize(DemuxerStream* demuxer_stream,
                           const base::Closure& callback,
                           const StatisticsCallback& stats_callback) OVERRIDE;
-  virtual void ProduceVideoFrame(
-      scoped_refptr<VideoFrame> video_frame) OVERRIDE;
+  virtual void Read(const ReadCB& callback) OVERRIDE;
   virtual gfx::Size natural_size() OVERRIDE;
 
  private:
-  // VideoDecodeEngine::EventHandler interface.
-  virtual void OnInitializeComplete(bool success) OVERRIDE;
-  virtual void OnUninitializeComplete() OVERRIDE;
-  virtual void OnFlushComplete() OVERRIDE;
-  virtual void OnSeekComplete() OVERRIDE;
-  virtual void OnError() OVERRIDE;
-  virtual void ProduceVideoSample(scoped_refptr<Buffer> buffer) OVERRIDE;
-  virtual void ConsumeVideoFrame(
-      scoped_refptr<VideoFrame> frame,
-      const PipelineStatistics& statistics) OVERRIDE;
-
   enum DecoderState {
-    kUnInitialized,
-    kInitializing,
+    kUninitialized,
     kNormal,
     kFlushCodec,
     kDecodeFinished,
-    kPausing,
-    kFlushing,
-    kStopped
   };
 
-  void OnFlushComplete(const base::Closure& callback);
-  void OnSeekComplete(const base::Closure& callback);
+  // Carries out the reading operation scheduled by Read().
+  void DoRead(const ReadCB& callback);
 
-  // TODO(scherkus): There are two of these to keep read completions
-  // asynchronous and media_unittests passing. Remove.
-  void OnReadComplete(const scoped_refptr<Buffer>& buffer);
-  void OnReadCompleteTask(const scoped_refptr<Buffer>& buffer);
+  // Reads from the demuxer stream with corresponding callback method.
+  void ReadFromDemuxerStream();
+  void DecodeBuffer(const scoped_refptr<Buffer>& buffer);
 
-  // Flush the output buffers that we had held in Paused state.
-  void FlushBuffers();
+  // Carries out the decoding operation scheduled by DecodeBuffer().
+  //
+  // TODO(scherkus): mandate that DemuxerStream::Read() execute asynchronously

[acolwell GONE FROM CHROMIUM, 2011/11/03 20:00:43]

Will making Read() async really remove the need for a post? If we did that
wouldn't it be likely the callback would then be called on the Demuxer thread
which would then require a post to the video decode thread? 

I'm fine with mandating Read() be asynchronous, but if doing so really isn't
going remove the need for a Post then I think this part of the comment should be
removed.

[scherkus (not reviewing), 2011/11/03 20:34:38]

This TODO has been replaced w/ the TODO inside the .cc

+  // so that a forced-task-repost isn't necessary.
+  void DoDecodeBuffer(const scoped_refptr<Buffer>& buffer);
 
-  // Injection point for unittest to provide a mock engine.  Takes ownership of
-  // the provided engine.
-  virtual void SetVideoDecodeEngineForTest(VideoDecodeEngine* engine);
+  // Delivers the frame to |read_cb_| and resets the callback.
+  void DeliverFrame(const scoped_refptr<VideoFrame>& video_frame);
 
   MessageLoop* message_loop_;
 
-  PtsStream pts_stream_;  // Stream of presentation timestamps.
+  PtsStream pts_stream_;
   DecoderState state_;
   scoped_ptr<VideoDecodeEngine> decode_engine_;
 
-  base::Closure initialize_callback_;
-  base::Closure uninitialize_callback_;
-  base::Closure flush_callback_;
-  FilterStatusCB seek_cb_;
   StatisticsCallback statistics_callback_;
 
-  // Hold video frames when flush happens.
-  std::deque<scoped_refptr<VideoFrame> > frame_queue_flushed_;
+  ReadCB read_cb_;
 
   // TODO(scherkus): I think this should be calculated by VideoRenderers based
   // on information provided by VideoDecoders (i.e., aspect ratio).