The callback has to go through VoEBaseImpl since VoEChannel is internal to voice engine. TEST=compile R=tommi@webrtc.org Review URL: https://webrtc-codereview.appspot.com/7769005 git-svn-id: http://webrtc.googlecode.com/svn/trunk@5458 4adac7df-926f-26a2-2b94-8c16560cd09d