Add UMA stats for the wildcard login check.

Enterprise devices make an online check with GAIA to reconfirm login
permission when users login in via wildcards in the login whitelist
device setting. This adds UMA stats to quantify the slow-down incurred
on the login flow.

BUG=chromium:336284
TEST=None

Review URL: https://codereview.chromium.org/152323005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249689 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249689