GitLab

Make sure to damage the previous underlay area
when switching underlays so that it is repainted.

BUG=854790
TEST=UnderlayTest.UpdateDamageWhenChangingUnderlays

Change-Id: Idec0e30e0cf65e4937f85dfd3bdfd9ba4120d5fe
Reviewed-on: https://chromium-review.googlesource.com/1161393
Commit-Queue: Fritz Koenig <frkoenig@chromium.org>
Reviewed-by: Daniele Castagna <dcastagna@chromium.org>
Cr-Commit-Position: refs/heads/master@{#580957}