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..8cb1770fed9d34239d6d0d897d2c208339a81098 100644
--- a/media/audio/audio_manager.h
+++ b/media/audio/audio_manager.h
@@ -241,6 +241,12 @@ 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.
+  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(