Add GetPreferredFormats method to media::VideoCapturerSource.

media/capture/video_capturer_source.cc

Index: media/capture/video_capturer_source.cc
diff --git a/media/capture/video_capturer_source.cc b/media/capture/video_capturer_source.cc
index bafdf4216fd9c91b170e6b81c8af5aa48ccc1609..7ff99155daf7899762170eb43f136cfa2e69c91b 100644
--- a/media/capture/video_capturer_source.cc
+++ b/media/capture/video_capturer_source.cc
@@ -13,4 +13,12 @@ namespace media {
 // to generate symbols across linking units.
 VideoCapturerSource::~VideoCapturerSource() {}
 
+void VideoCapturerSource::GetCurrentSupportedFormats(
+    int max_requested_width,
+    int max_requested_height,
+    double max_requested_frame_rate,
+    const VideoCaptureDeviceFormatsCB& callback) {
+  callback.Run(GetPreferredFormats());
+}
+
 }  // namespace media