GitLab

Start is deferred in relation to Stop, and when they're both called
within the Start interval, the end result was started.
Relands crrev.com/255322, fixing race condition in the test.

BUG=347887,349987

Review URL: https://codereview.chromium.org/188653003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255974 0039d316-1c4b-4281-b951-d872f2087c98