The Blink bots used to fetch layout tests results are not part of the default CQ trybot set.

Since the rebaseline process touches their expectations, it seems like a good idea to gate the commit on these Blink bots being green.  Otherwise, if something goes wrong with the rebaseline, it is possible for CQ to land the CL and only find out about breakage from the waterfall.

rebaseline-cl has access to all this info -- why not add Cq-Include-Trybots: <extra Blink bots> to the CL when a rebaseline is triggered?