GitLab

There is a policy "DeviceOffHours" which defines some time intervals
when some policies gets deleted from policy blob. Among them there is a
policy "DeviceGuestModeEnabled". If it's set to false after removing it
from policy blob it should default to "true", thus allowing browsing as
a guest.

Before: There is a button on login screen "Browser as Guest", because
policy "DeviceGuestModeEnabled" defaulted to "true" after deleting it
from policy blob. But when pressing it Chrome restarts and tries to
initialize profile synchronously. But "DeviceOffHours" doesn't get
applied because it's a policy that relies on time, and makes async DBus
call. So DeviceOffHoursController assumes that time is not reliable and
logs out the user.

After: Assume that time is reliable until the response from DBus call
arrived, thus allowing synchronous profile initialization to finish.
After finishing, response from DBus call arrives and corresponding
actions are taken (log user out if time is not synchronized).

User log out flow:
* DeviceOffHoursController::UpdateOffHoursMode               =>
* DeviceOffHoursController::SetOffHoursMode                  =>
* DeviceOffHoursController::OffHoursModeIsChanged            =>
* DeviceSettingsService::Load                                =>
* DeviceSettingsService::HandleCompletedOperation            =>
* DeviceSettingsService::NotifyDeviceSettingsUpdated         =>
* DeviceSettingsProvider::DeviceSettingsUpdated              =>
* DeviceSettingsProvider::UpdateAndProceedStoring            =>
* DeviceSettingsProvider::UpdateFromService                  =>
* DeviceSettingsProvider::UpdateValuesCache                  =>
* DeviceSettingsProvider::DecodePolicies                     =>
* DecodeLoginPolicies (in device_settings_provider.cc)       =>
* DecodeLoginPolicies changes CrosSettings                   =>
* CrosSettings change gets observed by ChromeUserManagerImpl =>
* UserManagerBase::NotifyUsersSignInConstraintsChanged       =>
* UserSessionManager::OnUsersSignInConstraintsChanged        =>
* AttemptUserExit

Test: Set DeviceGuestModeEnabled to "false", Configure "DeviceOffHours"
policy to have an interval from Monday 12:00am till Sunday 11:30pm.
During an Off Hours interval sign in to the device, disable all the
network connections. Exptectation: user will be kicked out as soon
network connections are gone.

Bug: 930567
Change-Id: I4f7fd429ba7cb64cf99a943e1f5e8686801279d5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1699667
Commit-Queue: Askar Aitzhan <askaraitzhan@google.com>
Reviewed-by: Maksim Ivanov <emaxx@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#682257}