cc: Handle future timebases properly in DelayBasedTimeSource
The existing code didn't anticipate negative values for
intervals_elapsed, which would round up towards 0 instead
of down towards 0 and cause the next frame to be posted
more than 1 vsync away.
This primarly cropped up on Windows machines, but only
for certain configurations.
BUG=262437
Review URL: https://chromiumcodereview.appspot.com/
22887010
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@217723 0039d316-1c4b-4281-b951-d872f2087c98