A bug is causing fraction lost to always be set to zero when calling ViERTP_RTCP::Get(Send|Receive)ChannelRtcpStatistics. Fix this and update tests to catch it. BUG= R=holmer@google.com, stefan@webrtc.org Review URL: https://webrtc-codereview.appspot.com/5219004 git-svn-id: http://webrtc.googlecode.com/svn/trunk@5235 4adac7df-926f-26a2-2b94-8c16560cd09d