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* Makes safety check elements focusable independently of their state.
* Attaches dynamic accessibility info to the elements to allow screen
  readers informing users about their state even in states they would
  otherwise not be focusable.
* DD: http://shortn/_uEauSbBMVy

Bug: 1015841
Change-Id: I52d2c932478d6e66661938b08f7d43f5d82a394a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2089698Reviewed-by: Esmael Elmoslimany <aee@chromium.org>
Commit-Queue: Rainhard Findling <rainhard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#748276}