Add GetAssociatedOutputDeviceID support to pulse.

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 b8e5cdcda4c606eaef98770e1507bbff99522855..7c744be6719a5bf46b3399cc1e746bb2e0711a67 100644
--- a/media/audio/pulse/pulse_util.h
+++ b/media/audio/pulse/pulse_util.h
@@ -75,6 +75,13 @@ bool CreateOutputStream(pa_threaded_mainloop** mainloop,
                         pa_stream_request_cb_t write_callback,
                         void* user_data);
 
+// Utility functions to match up outputs and inputs.
+std::string GetBusOfInput(const std::string& name,
+                          pa_threaded_mainloop* input_mainloop,
+                          pa_context* input_context);
+std::string GetOutputCorrespondingTo(const std::string& input_bus,
+                                     pa_threaded_mainloop* input_mainloop,
+                                     pa_context* input_context);
 }  // namespace pulse
 
 }  // namespace media