Use "application default" audio device as default PulseAudio device.

media/audio/pulse/pulse_util.h

Index: media/audio/pulse/pulse_util.h
diff --git a/media/audio/pulse/pulse_util.h b/media/audio/pulse/pulse_util.h
index a7fd875abcb5e173250a4c8347c30468807f3a54..b8e5cdcda4c606eaef98770e1507bbff99522855 100644
--- a/media/audio/pulse/pulse_util.h
+++ b/media/audio/pulse/pulse_util.h
@@ -53,8 +53,6 @@ int GetHardwareLatencyInBytes(pa_stream* stream,
 // otherwise false. |mainloop| and |context| have to be from a valid Pulse
 // threaded mainloop and the handle of the created stream will be returned by
 // |stream|.
-// TODO(grunell): Move this function to PulseAudioInputStream class since it's
-// only used there.
 bool CreateInputStream(pa_threaded_mainloop* mainloop,
                        pa_context* context,
                        pa_stream** stream,
@@ -67,10 +65,8 @@ bool CreateInputStream(pa_threaded_mainloop* mainloop,
 // otherwise false. This function will create a new Pulse threaded mainloop,
 // and the handles of the mainloop, context and stream will be returned by
 // |mainloop|, |context| and |stream|.
-// TODO(grunell): Move this function to PulseAudioOutputStream class since it's
-// only used there.
-bool CreateOutputStream(pa_threaded_mainloop* mainloop,
-                        pa_context* context,
+bool CreateOutputStream(pa_threaded_mainloop** mainloop,
+                        pa_context** context,
                         pa_stream** stream,
                         const AudioParameters& params,
                         const std::string& device_id,