factory_test_init: check state before starting factory program

This is the counter part of http://gerrit.chromium.org/gerrit/5867 ,
to verify state before starting factory UI.

BUG=chrome-os-partner:3107
TEST=see http://gerrit.chromium.org/gerrit/5867

Change-Id: Ibb20eb588fc914ce32fffec501303978b2870669
Reviewed-on: http://gerrit.chromium.org/gerrit/5868
Tested-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-by: Hung-Te Lin <hungte@chromium.org>