This will make it easier to get rid of super_mox.py

Bug: 984182
Change-Id: Ic6c9646b8a96ef05ac59293a62f68ad7db7dc2d0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1754977
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>
Reviewed-by: Robbie Iannucci <iannucci@chromium.org>