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There is currently no logging for any events in AutomaticRebootManager
and due to that it's hard to investigate issues with non-rebooting
devices.
These logs will be triggered on Chrome OS devices only:
 * on AutomaticRebootManager initialization
 * when reboot policies "UpdateLimit" or "RebootAfterUpdate" change
 * reboot is required due to an update

BUG=b/69546724

Change-Id: I488bb3b1b398d390f8ff2e5613a532e8494449bf
Reviewed-on: https://chromium-review.googlesource.com/808886Reviewed-by: Bartosz Fabianowski <bartfab@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Sergey Poromov <poromov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#522084}