Part 1: Plumb render view ID to render host

content/renderer/media/audio_output_ipc_impl.h

+// Copyright (c) 2012 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.
+//
+// MessageFilter that handles audio messages and delegates them to audio

[scherkus (not reviewing), 2012/08/03 21:12:52]

nit: we (media folks) typically have the class doc by the class as opposed to
the file

+// renderers. Created on render thread, AudioMessageFilter is operated on
+// IO thread (secondary thread of render process) it intercepts audio messages
+// and process them on IO thread since these messages are time critical.
+
+#ifndef CONTENT_RENDERER_MEDIA_AUDIO_OUTPUT_IPC_IMPL_H_
+#define CONTENT_RENDERER_MEDIA_AUDIO_OUTPUT_IPC_IMPL_H_
+
+#include "base/gtest_prod_util.h"
+#include "base/id_map.h"
+#include "base/shared_memory.h"
+#include "base/sync_socket.h"
+#include "content/common/content_export.h"
+#include "ipc/ipc_channel_proxy.h"
+#include "media/audio/audio_buffers_state.h"
+#include "media/audio/audio_output_ipc.h"
+
+class AudioMessageFilter;
+
+class CONTENT_EXPORT AudioOutputIPCImpl

[scherkus (not reviewing), 2012/08/03 21:12:52]

new classes in content should be under the content namespace

+    : public NON_EXPORTED_BASE(media::AudioOutputIPC) {
+ public:
+  explicit AudioOutputIPCImpl(int render_view_id);
+  virtual ~AudioOutputIPCImpl();
+
+  // media::AudioOutputIPC implementation.
+  virtual int AddDelegate(media::AudioOutputIPCDelegate* delegate) OVERRIDE;
+  virtual void RemoveDelegate(int id) OVERRIDE;
+  virtual void CreateStream(int stream_id,
+      const media::AudioParameters& params) OVERRIDE;
+  virtual void PlayStream(int stream_id) OVERRIDE;
+  virtual void PauseStream(int stream_id) OVERRIDE;
+  virtual void FlushStream(int stream_id) OVERRIDE;
+  virtual void CloseStream(int stream_id) OVERRIDE;
+  virtual void SetVolume(int stream_id, double volume) OVERRIDE;
+
+ private:
+
+  // Sends an IPC message using |filter_|.
+  bool Send(IPC::Message* message);
+
+  // Cached audio message filter (lives on the main render thread).
+  scoped_refptr<AudioMessageFilter> filter_;
+
+  // A map of stream ids to delegates.
+  IDMap<media::AudioOutputIPCDelegate> delegates_;
+
+  const int render_view_id_;
+
+  DISALLOW_COPY_AND_ASSIGN(AudioOutputIPCImpl);
+};
+
+#endif  // CONTENT_RENDERER_MEDIA_AUDIO_OUTPUT_IPC_IMPL_H_