Add struct traits for base::Value.

content/browser/renderer_host/media/video_capture_controller.cc

Index: content/browser/renderer_host/media/video_capture_controller.cc
diff --git a/content/browser/renderer_host/media/video_capture_controller.cc b/content/browser/renderer_host/media/video_capture_controller.cc
index 5f226b65422b880d21a94c1fe6795ede553eb2a5..fd1712795601155069c4dbd36a7ce97277f105e3 100644
--- a/content/browser/renderer_host/media/video_capture_controller.cc
+++ b/content/browser/renderer_host/media/video_capture_controller.cc
@@ -436,9 +436,8 @@ void VideoCaptureController::OnIncomingCapturedVideoFrame(
       frame->metadata()->SetDouble(VideoFrameMetadata::FRAME_RATE,
                                    video_capture_format_.frame_rate);
     }
-    std::unique_ptr<base::DictionaryValue> metadata(
-        new base::DictionaryValue());
-    frame->metadata()->MergeInternalValuesInto(metadata.get());
+    std::unique_ptr<base::DictionaryValue> metadata =
+        frame->metadata()->CopyInternalValues();
 
     // Only I420 and Y16 pixel formats are currently supported.
     DCHECK(frame->format() == media::PIXEL_FORMAT_I420 ||