GitLab

With system priority, the screenshot notification never auto dismisses and
remains forever.

BUG=987928

Change-Id: Ib83a156444970233b6d95654749dbd1cc9c4013e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1726764Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Tim Song <tengs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#682810}