Enable a11y audit for chrome://settings
Enabled the tests and fixed failure. Failure was due to transition obscuring elements in the UI.
Another failure was caused because there were no labels on the mic and camera drop downs.
Another failure was that there was no captions for a video element. This is used to capture a profile picture in chrome OS, so there wouldn't be any captions. This element is ignored in the a11y audit.
There was also an issue with the dispatching of events in the ensureTransitionEndEvent function that wouldn't allow the event to bubble.
BUG=311866
Committed: https://crrev.com/
34a84c6d1269332cc3ae2b8a50af489230c885de
Cr-Commit-Position: refs/heads/master@{#301266}
Review URL: https://codereview.chromium.org/
646853004
Cr-Commit-Position: refs/heads/master@{#305078}