Associate audio streams with their source/destination RenderView.

content/renderer/media/renderer_audio_output_device.cc

+// 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.
+
+#include "content/renderer/media/renderer_audio_output_device.h"
+
+#include "base/bind.h"
+#include "base/message_loop_proxy.h"
+#include "content/renderer/media/audio_message_filter.h"
+
+namespace content {
+
+RendererAudioOutputDevice::RendererAudioOutputDevice(
+    AudioMessageFilter* message_filter,
+    const scoped_refptr<base::MessageLoopProxy>& io_loop)
+    : AudioOutputDevice(message_filter, io_loop),
+      source_render_view_id_(MSG_ROUTING_NONE),
+      is_after_stream_created_(false) {
+}
+
+RendererAudioOutputDevice::~RendererAudioOutputDevice() {}
+
+void RendererAudioOutputDevice::Start() {
+  AudioOutputDevice::Start();

[scherkus (not reviewing), 2012/11/30 22:09:43]

q: should we DCHECK() here / in OnStart() that source_render_view_id_ has been
set? (or is it valid to be not set? you seem to handle that case but it's not
clear to me when/why that would happen)

[miu, 2012/12/01 00:40:17]

It's valid to not be set.  In fact, it's valid to not *ever* be set (example:
AudioRendererMixerManager).  This is one of the reasons I made the
"AssociateWithProducer" message separate, instead of just adding render_view_id
to the CreateStream message.

However, while plumbing render_view_id through the render-side mixer is
out-of-scope for this change, I *will* be attacking this problem in a later
change.  At that time, it might make sense to get rid of the
AssociateWithProducer message and just add render_view_id to CreateStream.

+  message_loop()->PostTask(FROM_HERE,
+      base::Bind(&RendererAudioOutputDevice::OnStart, this));
+}
+
+void RendererAudioOutputDevice::Stop() {
+  AudioOutputDevice::Stop();
+  message_loop()->PostTask(FROM_HERE,
+      base::Bind(&RendererAudioOutputDevice::OnStop, this));
+}
+
+void RendererAudioOutputDevice::SetSourceRenderView(int render_view_id) {
+  message_loop()->PostTask(FROM_HERE,
+      base::Bind(&RendererAudioOutputDevice::OnSourceChange, this,
+                 render_view_id));
+}
+
+void RendererAudioOutputDevice::OnStart() {
+  is_after_stream_created_ = true;
+  OnSourceChange(source_render_view_id_);
+}
+
+void RendererAudioOutputDevice::OnStop() {
+  is_after_stream_created_ = false;
+}
+
+void RendererAudioOutputDevice::OnSourceChange(int render_view_id) {
+  source_render_view_id_ = render_view_id;
+  if (is_after_stream_created_ && source_render_view_id_ != MSG_ROUTING_NONE) {
+    AudioMessageFilter* const filter =
+        static_cast<AudioMessageFilter*>(audio_output_ipc());
+    if (filter)
+      filter->AssociateStreamWithProducer(stream_id(), source_render_view_id_);
+  }
+}
+
+}  // namespace content