Replace AudioDecoder::ProduceAudioSamples/ConsumeAudioSamples with read callbacks.

media/filters/ffmpeg_video_decoder.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/filters/ffmpeg_video_decoder.h"
 
 #include "base/bind.h"
 #include "base/message_loop.h"
 #include "media/base/demuxer_stream.h"
 #include "media/base/filter_host.h"
@@ skipping 113 matching lines @@
     return;
   }
 
   decode_engine_->Flush();
   pts_stream_.Flush();
   state_ = kNormal;
   callback.Run();
 }
 
 void FFmpegVideoDecoder::Read(const ReadCB& callback) {
-  // TODO(scherkus): forced task post since VideoRendererBase::FrameReady() will
-  // call Read() on FFmpegVideoDecoder's thread as we executed |read_cb_|.
+  // Complete operation asynchronously on different stack of execution as per
+  // the API contract of VideoDecoder::Read()
   message_loop_->PostTask(FROM_HERE, base::Bind(
       &FFmpegVideoDecoder::DoRead, this, callback));
 }
 
 const gfx::Size& FFmpegVideoDecoder::natural_size() {
   return natural_size_;
 }
 
 void FFmpegVideoDecoder::DoRead(const ReadCB& callback) {
   DCHECK_EQ(MessageLoop::current(), message_loop_);
-  CHECK(!callback.is_null());
+  DCHECK(!callback.is_null());
   CHECK(read_cb_.is_null()) << "Overlapping decodes are not supported.";
 
   // This can happen during shutdown after Stop() has been called.
   if (state_ == kUninitialized) {
     return;
   }
 
   // Return empty frames if decoding has finished.
   if (state_ == kDecodeFinished) {
     callback.Run(VideoFrame::CreateEmptyFrame());
     return;
   }
 
   read_cb_ = callback;
   ReadFromDemuxerStream();
 }
 
 
 void FFmpegVideoDecoder::ReadFromDemuxerStream() {
   DCHECK_NE(state_, kUninitialized);
   DCHECK_NE(state_, kDecodeFinished);
   DCHECK(!read_cb_.is_null());
 
   demuxer_stream_->Read(base::Bind(&FFmpegVideoDecoder::DecodeBuffer, this));
 }
 
 void FFmpegVideoDecoder::DecodeBuffer(const scoped_refptr<Buffer>& buffer) {
-  // TODO(scherkus): forced task post since FFmpegDemuxerStream::Read() can
-  // immediately execute our callback on FFmpegVideoDecoder's thread.
+  // TODO(scherkus): fix FFmpegDemuxerStream::Read() to not execute our read
+  // callback on the same execution stack so we can get rid of forced task post.
   message_loop_->PostTask(FROM_HERE, base::Bind(
       &FFmpegVideoDecoder::DoDecodeBuffer, this, buffer));
 }
 
 void FFmpegVideoDecoder::DoDecodeBuffer(const scoped_refptr<Buffer>& buffer) {
   DCHECK_EQ(MessageLoop::current(), message_loop_);
   DCHECK_NE(state_, kUninitialized);
   DCHECK_NE(state_, kDecodeFinished);
   DCHECK(!read_cb_.is_null());
 
@@ skipping 72 matching lines @@
 
 void FFmpegVideoDecoder::DeliverFrame(
     const scoped_refptr<VideoFrame>& video_frame) {
   // Reset the callback before running to protect against reentrancy.
   ReadCB read_cb = read_cb_;
   read_cb_.Reset();
   read_cb.Run(video_frame);
 }
 
 }  // namespace media