when you move "focus" around the rows in the intent picker, ChromeVox doesn't announce anything. This is because the rows (buttons) aren't getting real focus but are instead getting MarkAsSelected/Unselected() calls.

We probably want to give them real focus and make the ink drop show highlight for focus (see https://codereview.chromium.org/2779113002/ )

(Also, we might want to do a more thorough a11y review for this entire dialog.)