The goal of this change is to unify tracing events styles and add trace events for all RTP traffic. BUG=1555 Review URL: https://webrtc-codereview.appspot.com/1290007 git-svn-id: http://webrtc.googlecode.com/svn/trunk@3806 4adac7df-926f-26a2-2b94-8c16560cd09d