Remove support for panel per profile type

The experiment was removed some time ago but there are some leftovers.

BUG=None
R=loislo@chromium.org

Review URL: https://codereview.chromium.org/148233002

git-svn-id: svn://svn.chromium.org/blink/trunk@165845 bbb929c8-8fbe-4397-9dbb-9b2b20218538