Mark Welcome Notification as Dismissed if Expiration Time Elapses

If Chrome is closed and the welcome notification time elapses,
mark the welcome notification as dismissed and don't show the
notification.

BUG=337503
R=dewittj@chromium.org

Review URL: https://codereview.chromium.org/148713004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@248809 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 248809