GitLab

Every so often, the Rosetta installer will call back
the provided "installation done" block more than once.
Protect against that.

Fixed: 1150097
Change-Id: Ib12db225e7c7f5ec7c7fa69dccdd12693575a944
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2545076Reviewed-by: Mark Mentovai <mark@chromium.org>
Commit-Queue: Avi Drissman <avi@chromium.org>
Auto-Submit: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#828484}