Reland of Add groupid for media devices. Group audio devices.

media/audio/audio_manager.h

Index: media/audio/audio_manager.h
diff --git a/media/audio/audio_manager.h b/media/audio/audio_manager.h
index 4c4cc8f59b4c77f66c8083ba30ceb6a2ec5e90b7..71d8cde17a364609780ee2ea64bdd5809d039d25 100644
--- a/media/audio/audio_manager.h
+++ b/media/audio/audio_manager.h
@@ -241,6 +241,13 @@ class MEDIA_EXPORT AudioManager {
   virtual std::string GetAssociatedOutputDeviceID(
       const std::string& input_device_id) = 0;
 
+  // These functions assign group ids to devices based on their device ids.
+  // The default implementation is an attempt to do this based on
+  // GetAssociatedOutputDeviceID. Must be called on the audio worker thread
+  // (see GetWorkerTaskRunner()).

[Guido Urdaneta, 2016/09/05 13:15:53]

Actually, the comment should say GetTaskRunner() instead of
GetWorkerTaskRunner().
Feel free to fix other instances if this as a drive-by.

[Max Morin, 2016/09/05 13:53:56]

Done.

+  virtual std::string GetGroupIDOutput(const std::string& output_device_id) = 0;
+  virtual std::string GetGroupIDInput(const std::string& input_device_id) = 0;
+
   // Create a new AudioLog object for tracking the behavior for one or more
   // instances of the given component.  See AudioLogFactory for more details.
   virtual std::unique_ptr<AudioLog> CreateAudioLog(