GitLab

Quads that require an overlay cannot be properly composited. This
replaces those quads with solid black. This will fix animations,
multiple protected videos and other cases that were trying to
composite protected video.

Also contains a few other required overlay fixes:
-fixes overlay prioritization sort for required overlays so the sort
is stable between them
-skips empty quads for overlays

BUG=b:155511837
TEST=Window and rotation animations no longer display encrypted content
when playing protected video on volteer

Change-Id: Ibd9b812e23e798aa80034862d2d957809bb0fe09
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2616743
Commit-Queue: Jeffrey Kardatzke <jkardatzke@google.com>
Reviewed-by: Daniele Castagna <dcastagna@chromium.org>
Cr-Commit-Position: refs/heads/master@{#842239}