GitLab

There was a race condition where GetTokenService could be called on an
already destroyed TokenServiceProvider (see linked bug for details).
Update Core to ensure TokenServiceProvider is not destroyed out from
under the token service task runner thread.

BUG=401119

Review URL: https://codereview.chromium.org/458753006

Cr-Commit-Position: refs/heads/master@{#289222}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@289222 0039d316-1c4b-4281-b951-d872f2087c98