Consolidate GetFrame and InsertPacket and move NACK list processing to after a packet has been successfully inserted.

TEST=trybots
BUG=1799
R=mikhal@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/1509004

git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@4080 4adac7df-926f-26a2-2b94-8c16560cd09d
9 files changed