Motown: Add ActiveMultistreamSource model in preparation for the ffmpeg demux with async I/O

services/media/framework_ffmpeg/ffmpeg_decoder_base.cc

 // Copyright 2016 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 "base/logging.h"
 #include "services/media/framework_ffmpeg/av_codec_context.h"
 #include "services/media/framework_ffmpeg/ffmpeg_decoder_base.h"
 
 namespace mojo {
 namespace media {
 
 FfmpegDecoderBase::FfmpegDecoderBase(AvCodecContextPtr av_codec_context)
     : av_codec_context_(std::move(av_codec_context)),
-      av_frame_ptr_(av_frame_alloc()) {
+      av_frame_ptr_(ffmpeg::AvFrame::Create()) {
   DCHECK(av_codec_context_);
 }
 
 FfmpegDecoderBase::~FfmpegDecoderBase() {}
 
 std::unique_ptr<StreamType> FfmpegDecoderBase::output_stream_type() {
   return AvCodecContext::GetStreamType(*av_codec_context_);
 }
 
 void FfmpegDecoderBase::Flush() {
@@ skipping 63 matching lines @@
   }
 
   av_packet_.size = 0;
   av_packet_.data = nullptr;
 
   return true;
 }
 
 }  // namespace media
 }  // namespace mojo