Performance issue and simplicity, this implementation skips conversion to VideoEngine's frame format and then back again to I420VideoFrame. BUG=2526 R=mflodman@webrtc.org Review URL: https://webrtc-codereview.appspot.com/3989004 git-svn-id: http://webrtc.googlecode.com/svn/trunk@5140 4adac7df-926f-26a2-2b94-8c16560cd09d