On device lockdown, always show the keyguard

Manual test steps:
1. Enable app pinning and disable "Ask for PIN before unpinning" setting
2. Pin an app (ie: Settings)
3. Lockdown from the power menu
Observe: user is brought to the keyguard, primary auth is required
to enter the device. After entering credential, the device is still in
app pinning mode.

Test: atest KeyguardViewMediatorTest
Test: manual steps outlined above
Bug: 218495634
Change-Id: I9a7c5e1acadabd4484e58573331f98dba895f2a2
Merged-In: I9a7c5e1acadabd4484e58573331f98dba895f2a2

packages/SystemUI/src/com/android/systemui/keyguard/KeyguardViewMediator.java

@@ -677,6 +677,13 @@ public class KeyguardViewMediator extends SystemUI implements Dumpable,
                 }
             }
         }
+
+        @Override
+        public void onStrongAuthStateChanged(int userId) {
+            if (mLockPatternUtils.isUserInLockdown(KeyguardUpdateMonitor.getCurrentUser())) {
+                doKeyguardLocked(null);
+            }
+        }
     };
 
     ViewMediatorCallback mViewMediatorCallback = new ViewMediatorCallback() {
@@ -1535,7 +1542,8 @@ public class KeyguardViewMediator extends SystemUI implements Dumpable,
         }
 
         // if another app is disabling us, don't show
-        if (!mExternallyEnabled) {
+        if (!mExternallyEnabled
+            && !mLockPatternUtils.isUserInLockdown(KeyguardUpdateMonitor.getCurrentUser())) {
             if (DEBUG) Log.d(TAG, "doKeyguard: not showing because externally disabled");
 
             mNeedToReshowWhenReenabled = true;