This includes if RTCP is received, but the number of packets received by the other end hasn't increased. Further, if no RTCP is received for more than 3 feedback intervals (3 seconds) we start reducing the estimate by 20%. This is put under an experiment. BUG=webrtc:6238 R=terelius@webrtc.org Review URL: https://codereview.webrtc.org/2262213002 . Cr-Commit-Position: refs/heads/master@{#14306}