Revert 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 3102b05f77d0e3e74687cfea390fac720d9fb391..71219d13f922d4f47f1b1dab763d7dc8612051c3 100644
--- a/webrtc/media/engine/webrtcvideoframe.cc
+++ b/webrtc/media/engine/webrtcvideoframe.cc
@@ -101,6 +101,11 @@
 
 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,