Add callback in VideoDecoder and AudioDecoder to return decoded frames.

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 c8481a24f92229b53459e76e59ede5f6d797699e..faa4b4a43208d4f041189964a7e8a02aa1151d54 100644
--- a/media/filters/ffmpeg_video_decoder.h
+++ b/media/filters/ffmpeg_video_decoder.h
@@ -34,7 +34,8 @@ class MEDIA_EXPORT FFmpegVideoDecoder : public VideoDecoder {
   // VideoDecoder implementation.
   virtual void Initialize(const VideoDecoderConfig& config,
                           bool low_delay,
-                          const PipelineStatusCB& status_cb) OVERRIDE;
+                          const PipelineStatusCB& status_cb,
+                          const OutputCB& output_cb) OVERRIDE;
   virtual void Decode(const scoped_refptr<DecoderBuffer>& buffer,
                       const DecodeCB& decode_cb) OVERRIDE;
   virtual void Reset(const base::Closure& closure) OVERRIDE;
@@ -49,15 +50,13 @@ class MEDIA_EXPORT FFmpegVideoDecoder : public VideoDecoder {
   enum DecoderState {
     kUninitialized,
     kNormal,
-    kFlushCodec,
     kDecodeFinished,
     kError
   };
 
   // Handles decoding an unencrypted encoded buffer.
-  void DecodeBuffer(const scoped_refptr<DecoderBuffer>& buffer);
   bool FFmpegDecode(const scoped_refptr<DecoderBuffer>& buffer,
-                    scoped_refptr<VideoFrame>* video_frame);
+                    bool* produced_frame);
 
   // Handles (re-)initializing the decoder with a (new) config.
   // Returns true if initialization was successful.
@@ -71,8 +70,7 @@ class MEDIA_EXPORT FFmpegVideoDecoder : public VideoDecoder {
 
   DecoderState state_;
 
-  // TODO(xhwang): Merge DecodeBuffer() into Decode() and remove this.
-  DecodeCB decode_cb_;
+  OutputCB output_cb_;
 
   // FFmpeg structures owned by this object.
   scoped_ptr<AVCodecContext, ScopedPtrAVFreeContext> codec_context_;