Make Android scrollbars not hit testable

Android scrollbars can't be interacted with by user input. This change
makes the SolidColorScrollbarLayer explicitly not hit testable to
ensure we don't enter any scrollbar scrolling code paths.

Also updated a few tests in that were
using a SolidColorScrollbarLayer as a generic (hit-testable) scrollbar
layer, which should instead use a PaintedScrollbarLayer.

Bug: 954366
Change-Id: Icae9f43e043c412603d30330386710bf59482fad
Commit-Queue: Nick Burris <>
Reviewed-by: David Bokan <>
Cr-Commit-Position: refs/heads/master@{#662839}
6 files changed