Keeps behavior for old periodic processing.
Rounding sleep time reduced chance for small bursts of busy-looping when
time approaches 0.
Also fixes a DCHECK which may trigger if there are rounding errors in
the timing.
Bug: webrtc:10809
Change-Id: Iba8450f906fd6ab3b1da97e04507b16ac6bbde3f
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/160000
Reviewed-by: Philip Eliasson <philipel@webrtc.org>
Commit-Queue: Erik Språng <sprang@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29841}