factory: Fix "ToT Chrome does not start on Factory images".

The "disable_chrome_restart flag" does not work properly on ToT if the file is
created before Chrome starts.

BUG=none
TEST=Manually boots a factory test image.

Change-Id: Ia97fb53ee0a57300035041ea1535852de59e3ffd
Reviewed-on: https://chromium-review.googlesource.com/269076
Tested-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-by: Wei-Ning Huang <wnhuang@chromium.org>
Commit-Queue: Hung-Te Lin <hungte@chromium.org>
1 file changed