Add audio signal to the ResourceScheduler.

content/browser/renderer_host/media/audio_renderer_host.cc

Index: content/browser/renderer_host/media/audio_renderer_host.cc
diff --git a/content/browser/renderer_host/media/audio_renderer_host.cc b/content/browser/renderer_host/media/audio_renderer_host.cc
index 8c06395eca68ecf94496c47946a26066060004d0..783dab17112fe71e362b7f27c1becfa3a8b591cd 100644
--- a/content/browser/renderer_host/media/audio_renderer_host.cc
+++ b/content/browser/renderer_host/media/audio_renderer_host.cc
@@ -10,6 +10,7 @@
 #include "base/metrics/histogram.h"
 #include "base/process/process.h"
 #include "content/browser/browser_main_loop.h"
+#include "content/browser/loader/resource_dispatcher_host_impl.h"
 #include "content/browser/media/audio_stream_monitor.h"
 #include "content/browser/media/capture/audio_mirroring_manager.h"
 #include "content/browser/media/media_internals.h"
@@ -273,19 +274,28 @@ void AudioRendererHost::DoNotifyStreamStateChanged(int stream_id,
         entry->stream_id(),
         base::Bind(&media::AudioOutputController::ReadCurrentPowerAndClip,
                    entry->controller()));
-    // TODO(dalecurtis): See about using AudioStreamMonitor instead.
-    if (!entry->playing()) {
-      entry->set_playing(true);
-      base::AtomicRefCountInc(&num_playing_streams_);
-    }
   } else {
     AudioStreamMonitor::StopMonitoringStream(
         render_process_id_, entry->render_frame_id(), entry->stream_id());
+  }
+
+  if (entry->playing() != is_playing) {

[mmenke, 2014/09/18 14:12:42]

Suggest making a method:

AudioRendererHost::UpdatePlayingStreams(entry, is_playing) or somesuch, and move
this entire code block there (including the initial if statement).  Then can use
it in DeleteEntry, too.

     // TODO(dalecurtis): See about using AudioStreamMonitor instead.

[aiolos (Not reviewing), 2014/09/18 01:13:24]

Dale, I wasn't quite sure where this TODO should go. Should I move it?

[DaleCurtis, 2014/09/18 17:51:23]

Hmm, I guess it's not actually all that clear. You can just remove it.

[aiolos (Not reviewing), 2014/09/18 21:46:47]

Done.

-    if (entry->playing()) {
-      entry->set_playing(false);
+    entry->set_playing(is_playing);
+    if (is_playing) {
+      base::AtomicRefCountInc(&num_playing_streams_);
+    } else {
       base::AtomicRefCountDec(&num_playing_streams_);
     }
+    if (ResourceDispatcherHostImpl::Get()) {
+      BrowserThread::PostTask(

[DaleCurtis, 2014/09/18 17:51:23]

Does this need to be a PostTask? You're already on the IO thread.

[aiolos (Not reviewing), 2014/09/18 21:46:47]

Done.

+          BrowserThread::IO,
+          FROM_HERE,
+          base::Bind(
+              &ResourceDispatcherHostImpl::OnAudioRenderHostStreamStateChanged,
+              base::Unretained(ResourceDispatcherHostImpl::Get()),
+              render_process_id_, entry->render_view_id(), is_playing));

[mmenke, 2014/09/18 14:12:42]

Can't we have multiple playing streams per RenderView?

[DaleCurtis, 2014/09/18 17:51:24]

Yeah, this should probably just return HasActiveAudio() instead of is_playing.

[aiolos (Not reviewing), 2014/09/18 21:46:47]

Changed to check that we're actually changing the active audio state to avoid
extraneous signals as well.

+    }
   }
 }
 
@@ -454,8 +464,18 @@ void AudioRendererHost::DeleteEntry(scoped_ptr<AudioEntry> entry) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   AudioStreamMonitor::StopMonitoringStream(
       render_process_id_, entry->render_frame_id(), entry->stream_id());
-  if (entry->playing())
+  if (entry->playing()) {
     base::AtomicRefCountDec(&num_playing_streams_);
+    if (ResourceDispatcherHostImpl::Get()) {
+      BrowserThread::PostTask(
+          BrowserThread::IO,
+          FROM_HERE,
+          base::Bind(
+              &ResourceDispatcherHostImpl::OnAudioRenderHostStreamStateChanged,
+              base::Unretained(ResourceDispatcherHostImpl::Get()),
+              render_process_id_, entry->render_view_id(), false));

[mmenke, 2014/09/18 14:12:42]

Same here - if we have two playing entries for a single render view, this
doesn't work.

[DaleCurtis, 2014/09/18 17:51:23]

Ditto.

[aiolos (Not reviewing), 2014/09/18 21:46:48]

Done.

+    }
+  }
 }
 
 void AudioRendererHost::ReportErrorAndClose(int stream_id) {