Goal is to ensure that unreviewed and untrusted code isn't sent through
CQ to try bots, by accident or through malicious intent.

R=agable@chromium.org
BUG=692613

Change-Id: I3f202685dff1ba0d609fadfd5725f98be833d325
Reviewed-on: https://chromium-review.googlesource.com/443351Reviewed-by: Aaron Gable <agable@chromium.org>
Commit-Queue: Andrii Shyshkalov <tandrii@chromium.org>