This also moves the packet feedback tracking to RtpVideoSender. Bug: webrtc:9517 Change-Id: Ifb1ff85051730108a0b0d1dd30f6f8595ad2af6e Reviewed-on: https://webrtc-review.googlesource.com/c/95920 Reviewed-by: Sebastian Jansson <srte@webrtc.org> Reviewed-by: Niels Moller <nisse@webrtc.org> Commit-Queue: Stefan Holmer <stefan@webrtc.org> Cr-Commit-Position: refs/heads/master@{#25019}