With rounding to the nearest the result can exceed the allocated
bitrate.
Bug: none
Change-Id: I0260a1640a1454951ca8e48fd447e047ef0271ee
Reviewed-on: https://webrtc-review.googlesource.com/69982
Reviewed-by: Erik Språng <sprang@webrtc.org>
Reviewed-by: Stefan Holmer <stefan@webrtc.org>
Commit-Queue: Sergey Silkin <ssilkin@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22879}