Reason for revert:
Break performance bots.
Original issue's description:
> Fix off-by-one bugs in video_coding::PacketBuffer when the buffer is filled with a single frame.
>
> BUG=webrtc:8028
>
> Review-Url: https://codereview.webrtc.org/2993513002
> Cr-Commit-Position: refs/heads/master@{#19209}
> Committed: ee13e8919cTBR=stefan@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=webrtc:8028
Review-Url: https://codereview.webrtc.org/2990183002
Cr-Commit-Position: refs/heads/master@{#19211}