Wire up the output device id and provide an implementation on Windows.

media/audio/win/audio_low_latency_output_win.h

Index: media/audio/win/audio_low_latency_output_win.h
diff --git a/media/audio/win/audio_low_latency_output_win.h b/media/audio/win/audio_low_latency_output_win.h
index eb0f5defc025afd2aa4e1c74aa1243adda335fc0..7884d8840f716d252e3d70dc45831bbc49c04566 100644
--- a/media/audio/win/audio_low_latency_output_win.h
+++ b/media/audio/win/audio_low_latency_output_win.h
@@ -122,6 +122,7 @@ class MEDIA_EXPORT WASAPIAudioOutputStream :
   // The ctor takes all the usual parameters, plus |manager| which is the
   // the audio manager who is creating this object.
   WASAPIAudioOutputStream(AudioManagerWin* manager,
+                          const std::string& device_id,
                           const AudioParameters& params,
                           ERole device_role);
 
@@ -220,6 +221,9 @@ class MEDIA_EXPORT WASAPIAudioOutputStream :
   // Length of the audio endpoint buffer.
   uint32 endpoint_buffer_size_frames_;
 
+  // The target device id or an empty string for the default device.
+  const std::string device_id_;
+
   // Defines the role that the system has assigned to an audio endpoint device.
   ERole device_role_;