update_engine: Add new rollback device policies.
Add rollback_to_target_version and rollback_allowed_milestones
device policies to update_engine's device_policy_provider.
These are matching the device policies introduced in crrev.com/c/916563.
rollback_to_target_version is describing what should happen when the
target_version_prefix policy has a lower value than the current OS
value. rollback_allowed_milestones is setting the number of milestones
rollback protection should be postponed for enterprise enrolled devices.
BUG=chromium:813036
TEST='cros_run_unit_tests --board=cyan --packages update_engine'
CQ-DEPEND=CL:923971
Change-Id: I310690882f10fcbb57cc9b957fad5388c3a06bc9
Reviewed-on: https://chromium-review.googlesource.com/928723
Commit-Ready: Marton Hunyady <hunyadym@chromium.org>
Tested-by: Marton Hunyady <hunyadym@chromium.org>
Reviewed-by: Amin Hassani <ahassani@chromium.org>
6 files changed