GitLab

Use a timer for setting the scan preview aria label with scan progress
updates.

Bug: 1059779
Change-Id: I83d59cb8b70e2fba262d52584deb532ebc9adcf9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2617358Reviewed-by: Jesse Schettler <jschettler@chromium.org>
Commit-Queue: Gavin Williams <gavinwill@chromium.org>
Cr-Commit-Position: refs/heads/master@{#842120}