Reland "Skip promoting SingleOnTop Overlay when contents don't change"

This is a reland of b4fd0cc9d68915dd21d270a10e7cfd4eecc69919

Original change's description:
> Skip promoting SingleOnTop Overlay when contents don't change
> 
> If a candidate content has not changed for 3 frames, do not promote it as
> Single On Top overlay as it can be just be flattened, allowing other
> strategies to kick in if possible.
> 
> Bug: 885180
> Test: SingleOverlayOnTopTest.DoNotPromoteIfPreviouslyPromoted
> Change-Id: I516dab628c129fe9fae09c713e2783a6ce889c56
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1521591
> Commit-Queue: Mark Yacoub <markyacoub@google.com>
> Reviewed-by: Daniele Castagna <dcastagna@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#645367}

Bug: 885180
Change-Id: Icec20424721fb8539eadc2763e4420125981ba65
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1658853
Commit-Queue: Daniele Castagna <dcastagna@chromium.org>
Reviewed-by: Daniele Castagna <dcastagna@chromium.org>
Cr-Commit-Position: refs/heads/master@{#669229}