This is a refactoring in preparation for creating small unit tests for the udp_transport module. BUG= TEST=unittest Review URL: https://webrtc-codereview.appspot.com/482004 git-svn-id: http://webrtc.googlecode.com/svn/trunk@2041 4adac7df-926f-26a2-2b94-8c16560cd09d