GitLab

Scroll indicator is drawn over UiElementContainerView's empty bottom
border to work around issue of drawing over top of Assistant cards.

Visibility of the scroll indicator view is synced to vertical scroll
bar update/visibility events.

Bug: b:112669597
Change-Id: Ib8ae57428bb827913957fdd92168868c181ab4d7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2024285Reviewed-by: Robert Flack <flackr@chromium.org>
Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
Commit-Queue: David Black <dmblack@google.com>
Cr-Commit-Position: refs/heads/master@{#736437}