Add new device ID unit tests to UserMediaClientImpl.

content/renderer/media/mock_media_stream_dispatcher.h

Index: content/renderer/media/mock_media_stream_dispatcher.h
diff --git a/content/renderer/media/mock_media_stream_dispatcher.h b/content/renderer/media/mock_media_stream_dispatcher.h
index d23f551786c0c483e2e8a64978f6322927e69920..6550031300dca7e92e8ac20ca520c4b7e09987fd 100644
--- a/content/renderer/media/mock_media_stream_dispatcher.h
+++ b/content/renderer/media/mock_media_stream_dispatcher.h
@@ -48,8 +48,9 @@ class MockMediaStreamDispatcher : public MediaStreamDispatcher {
   const StreamDeviceInfoArray& video_array() const { return video_array_; }
 
  private:
-  void AddAudioInputDeviceToArray(bool matched_output);
-  void AddVideoDeviceToArray(bool facing_user);
+  void AddAudioInputDeviceToArray(bool matched_output,
+                                  const std::string& device_id);
+  void AddVideoDeviceToArray(bool facing_user, const std::string& device_id);
 
   int audio_input_request_id_;
   base::WeakPtr<MediaStreamDispatcherEventHandler> event_handler_;