SyncPointManager never returns 0.

When the next sync point overflow occurs, it returns 1, not 0.

BUG=365904, 373452

Review URL: https://codereview.chromium.org/288153004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@270997 0039d316-1c4b-4281-b951-d872f2087c98
2 files changed