Reland of Delete method cricket::VideoFrame::Copy.

webrtc/media/engine/webrtcvideoframe.cc

Index: webrtc/media/engine/webrtcvideoframe.cc
diff --git a/webrtc/media/engine/webrtcvideoframe.cc b/webrtc/media/engine/webrtcvideoframe.cc
index 71219d13f922d4f47f1b1dab763d7dc8612051c3..3102b05f77d0e3e74687cfea390fac720d9fb391 100644
--- a/webrtc/media/engine/webrtcvideoframe.cc
+++ b/webrtc/media/engine/webrtcvideoframe.cc
@@ -103,11 +103,6 @@ webrtc::VideoRotation WebRtcVideoFrame::rotation() const {
   return rotation_;
 }
 
-VideoFrame* WebRtcVideoFrame::Copy() const {
-  return new WebRtcVideoFrame(video_frame_buffer_, rotation_, timestamp_us_,
-                              transport_frame_id_);
-}
-
 size_t WebRtcVideoFrame::ConvertToRgbBuffer(uint32_t to_fourcc,
                                             uint8_t* buffer,
                                             size_t size,