Add a method to tab_utils.h to find out whether a tab is playing audio.

content/browser/renderer_host/media/audio_renderer_host.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/browser/renderer_host/media/audio_renderer_host.h"
 
 #include "base/bind.h"
 #include "base/metrics/histogram.h"
 #include "base/process.h"
 #include "base/shared_memory.h"
@@ skipping 21 matching lines @@
 
   // Shared memory for transmission of the audio data.
   base::SharedMemory shared_memory;
 
   // The synchronous reader to be used by the controller. We have the
   // ownership of the reader.
   scoped_ptr<media::AudioOutputController::SyncReader> reader;
 
   // Set to true after we called Close() for the controller.
   bool pending_close;
+
+  int render_view_id;
 };
 
 AudioRendererHost::AudioEntry::AudioEntry()
     : stream_id(0),
-      pending_close(false) {
+      pending_close(false),
+      render_view_id(0) {

[miu, 2012/12/19 00:49:08]

nit: This should probably default to MSG_ROUTING_NONE instead of 0.

 }
 
 AudioRendererHost::AudioEntry::~AudioEntry() {}
 
 ///////////////////////////////////////////////////////////////////////////////
 // AudioRendererHost implementations.
 AudioRendererHost::AudioRendererHost(
-    media::AudioManager* audio_manager, MediaObserver* media_observer)
-    : audio_manager_(audio_manager),
+    int render_process_id,
+    media::AudioManager* audio_manager,
+    MediaObserver* media_observer)
+    : render_process_id_(render_process_id),
+      audio_manager_(audio_manager),
       media_observer_(media_observer) {
 }
 
 AudioRendererHost::~AudioRendererHost() {
   DCHECK(audio_entries_.empty());
 }
 
 void AudioRendererHost::OnChannelClosing() {
   BrowserMessageFilter::OnChannelClosing();
 
@@ skipping 212 matching lines @@
   // If we have created the controller successfully, create an entry and add it
   // to the map.
   entry->stream_id = stream_id;
   audio_entries_.insert(std::make_pair(stream_id, entry.release()));
   if (media_observer_)
     media_observer_->OnSetAudioStreamStatus(this, stream_id, "created");
 }
 
 void AudioRendererHost::OnAssociateStreamWithProducer(int stream_id,
                                                       int render_view_id) {
-  // TODO(miu): Will use render_view_id in upcoming change.
-  DVLOG(1) << "AudioRendererHost@" << this
-           << "::OnAssociateStreamWithProducer(stream_id=" << stream_id
-           << ", render_view_id=" << render_view_id << ")";
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  AudioEntry* entry = LookupById(stream_id);
+  if (!entry) {
+    SendErrorMessage(stream_id);
+    return;
+  }
+
+  entry->render_view_id = render_view_id;

[miu, 2012/12/19 00:49:08]

While you're here, could you add a comment:

TODO(miu): Merge "AssociateWithProducer" message into "CreateStream" message so
AudioRendererHost can assume a simpler "render_view_id is set once" scheme. 
http://crbug.com/166779

[Bernhard Bauer, 2013/02/05 18:45:18]

Done.

 }
 
 void AudioRendererHost::OnPlayStream(int stream_id) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 
   AudioEntry* entry = LookupById(stream_id);
   if (!entry) {
     SendErrorMessage(stream_id);
     return;
   }
 
   entry->controller->Play();
   if (media_observer_)
-    media_observer_->OnSetAudioStreamPlaying(this, stream_id, true);
+    media_observer_->OnSetAudioStreamPlaying(
+        this, stream_id, render_process_id_, entry->render_view_id, true);
 }
 
 void AudioRendererHost::OnPauseStream(int stream_id) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 
   AudioEntry* entry = LookupById(stream_id);
   if (!entry) {
     SendErrorMessage(stream_id);
     return;
   }
 
   entry->controller->Pause();
-  if (media_observer_)
-    media_observer_->OnSetAudioStreamPlaying(this, stream_id, false);
+  if (media_observer_) {
+    media_observer_->OnSetAudioStreamPlaying(
+        this, stream_id, render_process_id_, entry->render_view_id, false);
+  }
 }
 
 void AudioRendererHost::OnFlushStream(int stream_id) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 
   AudioEntry* entry = LookupById(stream_id);
   if (!entry) {
     SendErrorMessage(stream_id);
     return;
   }
@@ skipping 105 matching lines @@
   return NULL;
 }
 
 media::AudioOutputController* AudioRendererHost::LookupControllerByIdForTesting(
     int stream_id) {
   AudioEntry* const entry = LookupById(stream_id);
   return entry ? entry->controller : NULL;
 }
 
 }  // namespace content