media: scaffolding and plumbing for MojoRenderer{Impl, Service}

media/mojo/services/mojo_demuxer_stream_adapter.h

+// Copyright 2014 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.
+
+#ifndef MEDIA_MOJO_SERVICES_MOJO_DEMUXER_STREAM_ADAPTER_H_
+#define MEDIA_MOJO_SERVICES_MOJO_DEMUXER_STREAM_ADAPTER_H_
+
+#include <queue>
+
+#include "base/memory/weak_ptr.h"
+#include "media/base/audio_decoder_config.h"
+#include "media/base/demuxer_stream.h"
+#include "media/base/video_decoder_config.h"
+#include "media/mojo/interfaces/demuxer_stream.mojom.h"
+
+namespace media {
+
+// This class acts as a MojoRendererService-side stub for a real
+// media::DemuxerStream that is part of a media::Pipeline in a remote
+// application. Roughly speaking, it takes a mojo::DemuxerStreamPtr and exposes
+// it as a media::DemuxerStream for use by media components.
+class MojoDemuxerStreamAdapter : public media::DemuxerStream,
+                                 public mojo::DemuxerStreamClient {
+ public:
+  // |demuxer_stream| is connected to the mojo::DemuxerStream that |this| will
+  //     become the client of.
+  // |stream_ready_cb| will be invoked when |stream| has fully initialized
+  //     and |this| is ready for use.
+  // NOTE: Illegal to call any methods until |stream_ready_cb| is invoked.
+  MojoDemuxerStreamAdapter(mojo::DemuxerStreamPtr demuxer_stream,
+                           const base::Closure& stream_ready_cb);
+  virtual ~MojoDemuxerStreamAdapter();
+
+  // media::DemuxerStream implementation.
+  virtual void Read(const ReadCB& read_cb) OVERRIDE;
+  virtual AudioDecoderConfig audio_decoder_config() OVERRIDE;
+  virtual VideoDecoderConfig video_decoder_config() OVERRIDE;
+  virtual Type type() OVERRIDE;
+  virtual void EnableBitstreamConverter() OVERRIDE;
+  virtual bool SupportsConfigChanges() OVERRIDE;
+  virtual VideoRotation video_rotation() OVERRIDE;
+
+  // mojo::DemuxerStreamClient implementation.
+  virtual void OnStreamReady(mojo::ScopedDataPipeConsumerHandle pipe) OVERRIDE;
+  virtual void OnAudioDecoderConfigChanged(
+      mojo::AudioDecoderConfigPtr config) OVERRIDE;
+
+ private:
+  // The callback from |demuxer_stream_| that a read operation has completed.
+  // |read_cb| is a callback from the client who invoked Read() on |this|.
+  void OnBufferReady(mojo::DemuxerStream::Status status,
+                     mojo::MediaDecoderBufferPtr buffer);
+
+  // See constructor for descriptions.
+  mojo::DemuxerStreamPtr demuxer_stream_;
+  base::Closure stream_ready_cb_;
+
+  // The last ReadCB received through a call to Read().
+  // Used to store the results of OnBufferReady() in the event it is called
+  // with DemuxerStream::Status::kConfigChanged and we don't have an up to
+  // date AudioDecoderConfig yet. In that case we can't forward the results
+  // on to the caller of Read() until OnAudioDecoderConfigChanged is observed.
+  DemuxerStream::ReadCB read_cb_;
+
+  // The front of the queue is the current config. We pop when we observe
+  // DemuxerStatus::CONFIG_CHANGED.
+  std::queue<media::AudioDecoderConfig> config_queue_;
+
+  base::WeakPtrFactory<MojoDemuxerStreamAdapter> weak_factory_;
+  DISALLOW_COPY_AND_ASSIGN(MojoDemuxerStreamAdapter);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_MOJO_SERVICES_MOJO_DEMUXER_STREAM_ADAPTER_H_