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Add SnapshotRebootController that is responsible for rebooting the
device if no user is logged in.
SnapshotRebootController makes 3 attempts every 5 mins to reboot a
device if inside a snapshot update interval.

BUG=b:170187468
TEST=components_unittests

Change-Id: Ic19c2386d121e403d42546b25fd67c0c221d52b2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2584506
Commit-Queue: Polina Bondarenko <pbond@chromium.org>
Auto-Submit: Polina Bondarenko <pbond@chromium.org>
Reviewed-by: Yusuke Sato <yusukes@chromium.org>
Reviewed-by: Oleksandr Peletskyi <peletskyi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#844057}