Merge "Improve documentation for TrustManagerService#TrustState" into main

    private VirtualDeviceManagerInternal mVirtualDeviceManager;

    private enum TrustState {

        UNTRUSTED, // the phone is not unlocked by any trustagents

        TRUSTABLE, // the phone is in a semi-locked state that can be unlocked if

        // FLAG_GRANT_TRUST_TEMPORARY_AND_RENEWABLE is passed and a trustagent is trusted

        TRUSTED // the phone is unlocked

        // UNTRUSTED means that TrustManagerService is currently *not* giving permission for the

        // user's Keyguard to be dismissed, and grants of trust by trust agents are remembered in

        // the corresponding TrustAgentWrapper but are not recognized until the device is unlocked

        // for the user.  I.e., if the device is locked and the state is UNTRUSTED, it cannot be

        // unlocked by a trust agent.  Automotive devices are an exception; grants of trust are

        // always recognized on them.

        UNTRUSTED,

        // TRUSTABLE is the same as UNTRUSTED except that new grants of trust using

        // FLAG_GRANT_TRUST_TEMPORARY_AND_RENEWABLE are recognized for moving to TRUSTED.  I.e., if

        // the device is locked and the state is TRUSTABLE, it can be unlocked by a trust agent,

        // provided that the trust agent chooses to use Active Unlock.  The TRUSTABLE state is only

        // possible as a result of a downgrade from TRUSTED, after a trust agent used

        // FLAG_GRANT_TRUST_TEMPORARY_AND_RENEWABLE in its most recent grant.

        TRUSTABLE,

        // TRUSTED means that TrustManagerService is currently giving permission for the user's

        // Keyguard to be dismissed.  This implies that the device is unlocked for the user (where

        // the case of Keyguard showing but dismissible just with swipe counts as "unlocked").

        TRUSTED

    };

    @GuardedBy("mUserTrustState")