Add AudioBufferStream.

media/filters/decoder_stream.cc

Index: media/filters/decoder_stream.cc
diff --git a/media/filters/decoder_stream.cc b/media/filters/decoder_stream.cc
index 5c02547a2309e2b163ac242da56b7638b160c8d1..291af439a62428950005291de1ad3f495966af92 100644
--- a/media/filters/decoder_stream.cc
+++ b/media/filters/decoder_stream.cc
@@ -10,6 +10,7 @@
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/single_thread_task_runner.h"
+#include "media/base/audio_decoder.h"
 #include "media/base/bind_to_current_loop.h"
 #include "media/base/decoder_buffer.h"
 #include "media/base/demuxer_stream.h"
@@ -28,6 +29,11 @@ const char* GetTraceString<DemuxerStream::VIDEO>() {
   return "DecoderStream<VIDEO>::Decode";
 }
 
+template <>
+const char* GetTraceString<DemuxerStream::AUDIO>() {
+  return "DecoderStream<AUDIO>::Decode";
+}
+
 template <DemuxerStream::Type StreamType>
 DecoderStream<StreamType>::DecoderStream(
     const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
@@ -65,7 +71,6 @@ void DecoderStream<StreamType>::Initialize(DemuxerStream* stream,
   // TODO(xhwang): DecoderSelector only needs a config to select a decoder.
   decoder_selector_->SelectDecoder(
       stream,
-      StatisticsCB(),
       base::Bind(&DecoderStream<StreamType>::OnDecoderSelected,
                  weak_factory_.GetWeakPtr()));
 }
@@ -95,6 +100,12 @@ void DecoderStream<StreamType>::Read(const ReadCB& read_cb) {
     return;
   }
 
+  // If the decoder has queued output ready to go we don't need a demuxer read.
+  if (scoped_refptr<Output> output = decoder_->GetDecodeOutput()) {

[xhwang, 2014/03/05 00:40:46]

This is neat, but I am not sure whether it's more readable... See offline chats.

[rileya (GONE FROM CHROMIUM), 2014/03/05 08:08:28]

Done.

+    SatisfyRead(OK, output);

[xhwang, 2014/03/05 00:40:46]

Can we add a unit test to cover this logic?

[rileya (GONE FROM CHROMIUM), 2014/03/05 08:08:28]

Sounds good, will do.

[rileya (GONE FROM CHROMIUM), 2014/03/06 22:11:56]

Done. There's currently no tests for DecoderStream, so I added it to
VideoFrameStream's tests (and filed http://crbug.com/350072).

+    return;
+  }
+
   ReadFromDemuxerStream();
 }
 
@@ -185,6 +196,12 @@ bool DecoderStream<StreamType>::CanReadWithoutStalling() const {
   return decoder_->CanReadWithoutStalling();
 }
 
+template <>
+bool DecoderStream<DemuxerStream::AUDIO>::CanReadWithoutStalling() const {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  return true;
+}
+
 template <DemuxerStream::Type StreamType>
 void DecoderStream<StreamType>::OnDecoderSelected(
     scoped_ptr<Decoder> selected_decoder,
@@ -319,6 +336,7 @@ void DecoderStream<StreamType>::OnDecodeOutputReady(
     return;
   }
 
+  DCHECK(output);
   SatisfyRead(OK, output);
 }
 
@@ -387,12 +405,10 @@ void DecoderStream<StreamType>::ReinitializeDecoder() {
   DCHECK(task_runner_->BelongsToCurrentThread());
   DCHECK_EQ(state_, STATE_FLUSHING_DECODER) << state_;
 
-  // TODO(rileya): Specialize this for audio, or, better yet, change
-  // DemuxerStream config getters to be templated.
-  DCHECK(stream_->video_decoder_config().IsValidConfig());
+  DCHECK(StreamTraits::GetDecoderConfig(*stream_).IsValidConfig());
   state_ = STATE_REINITIALIZING_DECODER;
   decoder_->Initialize(
-      stream_->video_decoder_config(),
+      StreamTraits::GetDecoderConfig(*stream_),
       base::Bind(&DecoderStream<StreamType>::OnDecoderReinitialized,
                  weak_factory_.GetWeakPtr()));
 }
@@ -492,5 +508,6 @@ void DecoderStream<StreamType>::OnDecoderStopped() {
 }
 
 template class DecoderStream<DemuxerStream::VIDEO>;
+template class DecoderStream<DemuxerStream::AUDIO>;
 
 }  // namespace media