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 067c80fc1e6f3dc51edba87bdd1e946246e7e23a..4f89c8b85d100562d14cb891c6b11e8f67f247d1 100644
--- a/webrtc/media/engine/webrtcvideoframe.cc
+++ b/webrtc/media/engine/webrtcvideoframe.cc
@@ -76,6 +76,10 @@
 const rtc::scoped_refptr<webrtc::VideoFrameBuffer>&
 WebRtcVideoFrame::video_frame_buffer() const {
   return video_frame_buffer_;
+}
+
+VideoFrame* WebRtcVideoFrame::Copy() const {
+  return new WebRtcVideoFrame(video_frame_buffer_, rotation_, timestamp_us_);
 }
 
 size_t WebRtcVideoFrame::ConvertToRgbBuffer(uint32_t to_fourcc,