Adding debug mode for scrims

This makes every scrim to have very distinct color, helpful when trying to determine which scrim is shown right now.
It's not perfect as in some cases colors are overriden in ScrimController but it should be 90% accurate.

Bug: 213304101
Test: manual
Change-Id: Id24165a06caac453f7a4f1d6749dd2d271a63060
1 file changed