Specifically, UpDownUpAudioVideoTransportSequenceNumberRtx and AudioTransportSequenceNumber. TBR=stefan@webrtc.org Bug: webrtc:8878 Change-Id: I24ad65dc56068bb01c53d97511faadc22bd13c31 Reviewed-on: https://webrtc-review.googlesource.com/52161 Reviewed-by: Taylor Brandstetter <deadbeef@webrtc.org> Cr-Commit-Position: refs/heads/master@{#21992}