Add GetPreferredFormats method to media::VideoCapturerSource.

content/renderer/media/media_stream_video_capturer_source.cc

Index: content/renderer/media/media_stream_video_capturer_source.cc
diff --git a/content/renderer/media/media_stream_video_capturer_source.cc b/content/renderer/media/media_stream_video_capturer_source.cc
index 1a97c2d67a4b6452507090226da6fde1d370f6c4..d53f4d48c4299abce08046f1f2005d456bc5ba8f 100644
--- a/content/renderer/media/media_stream_video_capturer_source.cc
+++ b/content/renderer/media/media_stream_video_capturer_source.cc
@@ -209,6 +209,7 @@ class LocalVideoCapturerSource final : public media::VideoCapturerSource {
       int max_requested_height,
       double max_requested_frame_rate,
       const VideoCaptureDeviceFormatsCB& callback) override;
+  media::VideoCaptureFormats GetPreferredFormats() override;
   void StartCapture(const media::VideoCaptureParams& params,
                     const VideoCaptureDeliverFrameCB& new_frame_callback,
                     const RunningCallback& running_callback) override;
@@ -301,6 +302,10 @@ void LocalVideoCapturerSource::GetCurrentSupportedFormats(
                        weak_factory_.GetWeakPtr())));
 }
 
+media::VideoCaptureFormats LocalVideoCapturerSource::GetPreferredFormats() {
+  return media::VideoCaptureFormats();
+}
+
 void LocalVideoCapturerSource::StartCapture(
     const media::VideoCaptureParams& params,
     const VideoCaptureDeliverFrameCB& new_frame_callback,