Chrome Version: 64.0.3240.0

Steps To Reproduce:
(1) Open directory w/ 1+ file(s).
(2) Switch to Thumbnail View
(3) Turn ChromeVox ON
(4) Select 1+ file(s).
(5) Swipe around the left-top corner of each thumbanil to focus on the blue or gray checkmark.

Expected Result:
The screenreader should give information about the checkmark.
It is a checkbox and it is checked (or not checked).

Actual Result:
It says nothing.
It will read the file name as you swipe each thumbanil, but will do nothing on the checkmark.