GitLab

This is to make sure that starting the proxy in UpgradeInstance()
will always succeed even after Chrome crashes and restarting.

Once b/142140355 is fixed, the proxy will detect Chrome crashes by
itself and exit, but in theory, the proxy may exit after restarted
Chrome calls UpgradeInstance(). This CL is to prevent the race.

BUG=b:143175381
TEST=kill Chrome, verify restarted Chrome can start ARCVM

Change-Id: Id408c6525f5b7a53d095ce36777a4300ec313cb3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1874788Reviewed-by: Hidehiko Abe <hidehiko@chromium.org>
Commit-Queue: Yusuke Sato <yusukes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#708656}