Getting rid of AudioHardwareConfig and its synchronous IPC.

content/renderer/media/audio_device_factory.h

Index: content/renderer/media/audio_device_factory.h
diff --git a/content/renderer/media/audio_device_factory.h b/content/renderer/media/audio_device_factory.h
index 66936892b0bbbb90d0556b0d615e5c492eaea2a1..0ba01d0354609b59e1e24b949573ef4d29972223 100644
--- a/content/renderer/media/audio_device_factory.h
+++ b/content/renderer/media/audio_device_factory.h
@@ -48,6 +48,9 @@ class CONTENT_EXPORT AudioDeviceFactory {
     kSourceLast = kSourceWebAudioExact  // Only used for validation of format.
   };
 
+  // TODO(olka, guidou): replace with actulal frame id everywhere.

[Guido Urdaneta, 2016/07/06 14:16:16]

fix typo: s/actulal/actual

+  enum { kUnknownFrameIdForDefaultDevice = 1 };

[DaleCurtis, 2016/07/06 18:53:36]

Why do we need this? Should we instead just have a method which doesn't take a
render frame id?

[miu, 2016/07/06 19:10:57]

Not sure if I understand everything going on here, but we should never allow
audio output from a render frame without associating the output stream with the
frame ID. Otherwise, several important browser-level features will break: the
audio indicator, tab OOM-killer management, tab mute, tab capture, etc.

What worries me is that we currently need this "unknown" enum. That infers there
is already broken code creating audio output without specifying its source
render frame.

IIRC, I had a DCHECK in AudioRendererHost to prevent streams with invalid render
frame IDs from being created. Did someone get rid of that?

[o1ka, 2016/07/13 09:52:41]

removed

+
   // Creates a sink for AudioRendererMixer.
   // |render_frame_id| refers to the RenderFrame containing the entity
   // producing the audio. If |session_id| is nonzero, it is used by the browser
@@ -85,6 +88,7 @@ class CONTENT_EXPORT AudioDeviceFactory {
                                  const url::Origin& security_origin);
 
   // A helper to get device info in the absence of AudioOutputDevice.
+  // Must be called on renderer thread only.
   static media::OutputDeviceInfo GetOutputDeviceInfo(
       int render_frame_id,
       int session_id,