Fix automation test login mode.
Fix automation test login mode.

BUG=none
TEST=automation tests with --login-screen=login should work.

Review URL: http://codereview.chromium.org/2968001

git-svn-id: http://src.chromium.org/svn/trunk/src@51964 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 8d0e0e660356aa6671af15350d23c1534180144e
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser