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 e39cc6104e5ee5c23166ab3d5dc3a12c4aa07397..be7100feaf91ab089d240a9930663c680071f424 100644
--- a/content/browser/renderer_host/media/video_capture_controller.cc
+++ b/content/browser/renderer_host/media/video_capture_controller.cc
@@ -393,9 +393,8 @@ 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 ||