Do not show first-run UI for ephemeral users.

TEST=manually
BUG=346261
R=nkostylev@chromium.org

Review URL: https://codereview.chromium.org/178203002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254473 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 254473