GitLab

Unintuitively, it seems this can be called more than once if a close is
confirmed by the user but later aborted.

Bug: 1152284
Change-Id: I89d45ae0eadf3248fccd983406fe0dc5d050afd0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2570332Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Evan Stade <estade@chromium.org>
Cr-Commit-Position: refs/heads/master@{#833425}