Support Opus Ambisonics playback

media/blink/webaudiosourceprovider_impl.cc

Index: media/blink/webaudiosourceprovider_impl.cc
diff --git a/media/blink/webaudiosourceprovider_impl.cc b/media/blink/webaudiosourceprovider_impl.cc
index 825bd5169fdd9fcec5979ca35cc92b03f5eb8dd9..ff9fc890e4efc9c27a5337f527ceeef359d1c3f3 100644
--- a/media/blink/webaudiosourceprovider_impl.cc
+++ b/media/blink/webaudiosourceprovider_impl.cc
@@ -253,8 +253,18 @@ bool WebAudioSourceProviderImpl::SetVolume(double volume) {
 
 OutputDeviceInfo WebAudioSourceProviderImpl::GetOutputDeviceInfo() {
   base::AutoLock auto_lock(sink_lock_);
-  return sink_ ? sink_->GetOutputDeviceInfo()
-               : OutputDeviceInfo(OUTPUT_DEVICE_STATUS_ERROR_NOT_FOUND);
+  OutputDeviceInfo info;
+
+  if (sink_) {
+    info = sink_->GetOutputDeviceInfo();

[DaleCurtis, 2017/04/06 19:44:42]

Instead of returning the true sink parameters when WebAudio is connected, I
think you instead want to return some custom set of parameters from the WebAudio
|client_|. I.e. whatever channel count its configured for along with the sample
rate its currently using.

[flim-chromium, 2017/04/07 22:01:43]

It looks like the |client_| params are set only in
WebAudioSourceProviderImpl::OnSetFormat, which is called from AudioRendererImpl
after this function is called?

[DaleCurtis, 2017/04/10 19:38:51]

Yes, that's how it works today, but I  think we need it the other way around, so
that WebAudio can specify it wants all channels instead of just whatever the
hardware layout can handle. +rtoy for commentary.

[Raymond Toy, 2017/04/11 21:51:38]

That's probably the right thing to do because some day we want an audio context
to select the sample rate if possible (or internally resample if necessary).

I don't think we should block this CL on this.  If hongchan@ is happy that we
know get all the channels available, I'm good with it.

+    if (client_) {
+      info.SetIsWebAudioSource(true);
+    }
+  } else {
+    info = OutputDeviceInfo(OUTPUT_DEVICE_STATUS_ERROR_NOT_FOUND);
+  }
+
+  return info;
 }
 
 bool WebAudioSourceProviderImpl::CurrentThreadIsRenderingThread() {