GitLab

Use ChromeViewsDelegate/WidgetObserver combination to ensure that all
widgets are tested for accessibility as they become hidden or visible
in a browsertest.

The test goes through the View entire subtree and ensure any focusable
View has an accessible name.

Bug: 819350
Change-Id: I213e02bcfb1ec64aefc528cbda6a8a2a1d7bd0d0
Reviewed-on: https://chromium-review.googlesource.com/951933Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Trent Apted <tapted@chromium.org>
Commit-Queue: Aaron Leventhal <aleventhal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#545904}