GitLab

- also added preventive coding around registering for notification.

BUG=226128
TEST=verify per bug rpt


Review URL: https://chromiumcodereview.appspot.com/13674016

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@192831 0039d316-1c4b-4281-b951-d872f2087c98