Modifies the Trust Agent API to support Active Unlock.

Details for the design are in go/android-active-unlock-t and
go/android-active-unlock-t-api. This change
defines the API without implementing its use.

Test: non-functional API change. Existing regression tests check for regressions.
Test: manually verified smart lock still revokes trust when bluetooth
device disconnected
Bug: 213631675
Bug: 213631677
Bug: 213631672
Bug: 213911325
CTS-Coverage-Bug: 213944235

Change-Id: I206f3e5c5c456a7433be325ea0186b79319d3a66

core/java/android/service/trust/TrustAgentService.java

@@ -114,15 +114,47 @@ public class TrustAgentService extends Service {
      */
     public static final int FLAG_GRANT_TRUST_DISMISS_KEYGUARD = 1 << 1;
 
+    /**
+     * Flag for {@link #grantTrust(CharSequence, long, int)} indicating the platform should
+     * automatically remove trust after some conditions are met (detailed below) with the option for
+     * the agent to renew the trust again later.
+     *
+     * <p>After this is called, the agent will grant trust until the platform thinks an active user
+     * is no longer using that trust. For example, if the user dismisses keyguard, the platform will
+     * remove trust (this does not automatically lock the device).
+     *
+     * <p>When the platform internally removes the agent's trust in this manner, an agent can
+     * re-grant it (via a call to grantTrust) without the user having to unlock the device through
+     * another method (e.g. PIN). This renewable state only persists for a limited time.
+     *
+     * TODO(b/213631675): Remove @hide
+     * @hide
+     */
+    public static final int FLAG_GRANT_TRUST_TEMPORARY_AND_RENEWABLE = 1 << 2;
+
+    /**
+     * Flag for {@link #grantTrust(CharSequence, long, int)} indicating that the message should
+     * be displayed to the user.
+     *
+     * Without this flag, the message passed to {@code grantTrust} is only used for debugging
+     * purposes. With the flag, it may be displayed to the user as the reason why the device is
+     * unlocked.
+     *
+     * TODO(b/213911325): Remove @hide
+     * @hide
+     */
+    public static final int FLAG_GRANT_TRUST_DISPLAY_MESSAGE = 1 << 3;
+
     /** @hide */
     @Retention(RetentionPolicy.SOURCE)
     @IntDef(flag = true, prefix = { "FLAG_GRANT_TRUST_" }, value = {
             FLAG_GRANT_TRUST_INITIATED_BY_USER,
             FLAG_GRANT_TRUST_DISMISS_KEYGUARD,
+            FLAG_GRANT_TRUST_TEMPORARY_AND_RENEWABLE,
+            FLAG_GRANT_TRUST_DISPLAY_MESSAGE,
     })
     public @interface GrantTrustFlags {}
 
-
     /**
      * Int enum indicating that escrow token is active.
      * See {@link #onEscrowTokenStateReceived(long, int)}
@@ -264,6 +296,22 @@ public class TrustAgentService extends Service {
     public void onUnlockAttempt(boolean successful) {
     }
 
+    /**
+     * Called when the user has interacted with the locked device such that they likely want it
+     * to be unlocked. This approximates the timing when, for example, the platform would check for
+     * face authentication to unlock the device.
+     *
+     * To attempt to unlock the device, the agent needs to call
+     * {@link #grantTrust(CharSequence, long, int)}.
+     *
+     * @see #FLAG_GRANT_TRUST_TEMPORARY_AND_RENEWABLE
+     *
+     * TODO(b/213631672): Hook up call from system server & SystemUI, then un-hide
+     * @hide
+     */
+    public void onUserRequestedUnlock() {
+    }
+
     /**
      * Called when the timeout provided by the agent expires.  Note that this may be called earlier
      * than requested by the agent if the trust timeout is adjusted by the system or
@@ -563,6 +611,22 @@ public class TrustAgentService extends Service {
         }
     }
 
+    /**
+     * Locks the user.
+     *
+     * This revokes any trust granted by this agent and shows keyguard for the user if it is not
+     * currently shown for them. Other users are not affected. Note that this is in contrast to
+     * {@link #revokeTrust()} which does not show keyguard if it is not already shown.
+     *
+     * If the user has no auth method specified, then keyguard will still be shown but can be
+     * dismissed normally.
+     *
+     * TODO(b/213631675): Implement & make public
+     * @hide
+     */
+    public final void lockUser() {
+    }
+
     /**
      * Request showing a transient error message on the keyguard.
      * The message will be visible on the lock screen or always on display if possible but can be

services/core/java/com/android/server/trust/TrustAgentWrapper.java

@@ -123,6 +123,7 @@ public class TrustAgentWrapper {
         public void handleMessage(Message msg) {
             switch (msg.what) {
                 case MSG_GRANT_TRUST:
+                    // TODO(b/213631675): Respect FLAG_GRANT_TRUST_TEMPORARY_AND_RENEWABLE
                     if (!isConnected()) {
                         Log.w(TAG, "Agent is not connected, cannot grant trust: "
                                 + mName.flattenToShortString());