Reason for revert: Breaks bot. Original issue's description: > Change type of pid_diff (int16_t -> uint8_t) according to updates in RTP payload profile. Max p_diff is 8 bits. > > Change type of number of reference pictures (size_t -> uint8_t). Max is 2 bits. > > Size of WebRtcRTPHeader: 4352 -> 1784 bytes. > > BUG=webrtc:5144, chromium:500602 > > Committed: https://crrev.com/81c5c7f8157f767747bd97419eb0a589207354cf > Cr-Commit-Position: refs/heads/master@{#10504} TBR=stefan@webrtc.org,mflodman@webrtc.org NOPRESUBMIT=true NOTREECHECKS=true NOTRY=true BUG=webrtc:5144, chromium:500602 Review URL: https://codereview.webrtc.org/1423493005 Cr-Commit-Position: refs/heads/master@{#10508}