Allow multiple concurrent Decode() requests in VideoDecoder interface.

media/filters/decoder_stream.h

Index: media/filters/decoder_stream.h
diff --git a/media/filters/decoder_stream.h b/media/filters/decoder_stream.h
index 2fd2a552d2706395f748630aa4746a324dcfbd0d..2c413f2b1c973de43712135fc0dbe070c11fa1e9 100644
--- a/media/filters/decoder_stream.h
+++ b/media/filters/decoder_stream.h
@@ -87,6 +87,9 @@ class MEDIA_EXPORT DecoderStream {
   // behavior.
   bool CanReadWithoutStalling() const;
 
+  // Returns true if one more decode request can be submitted to the decoder.
+  bool CanDecodeAnotherBuffer() const;
+
   // Allows callers to register for notification of splice buffers from the
   // demuxer.  I.e., DecoderBuffer::splice_timestamp() is not kNoTimestamp().
   typedef base::Callback<void(base::TimeDelta)> SpliceObserverCB;
@@ -180,6 +183,11 @@ class MEDIA_EXPORT DecoderStream {
   SpliceObserverCB splice_observer_cb_;
   ConfigChangeObserverCB config_change_observer_cb_;
 
+  // Decoded buffers that haven't been read yet. Used when the decoder supports
+  // parallel decoding.
+  std::list<scoped_refptr<Output> > ready_output_buffers_;
+  int pending_decode_requests_;
+
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<DecoderStream<StreamType> > weak_factory_;
 
@@ -191,6 +199,9 @@ class MEDIA_EXPORT DecoderStream {
 template <>
 bool DecoderStream<DemuxerStream::AUDIO>::CanReadWithoutStalling() const;
 
+template <>
+bool DecoderStream<DemuxerStream::AUDIO>::CanDecodeAnotherBuffer() const;
+
 typedef DecoderStream<DemuxerStream::VIDEO> VideoFrameStream;
 typedef DecoderStream<DemuxerStream::AUDIO> AudioBufferStream;