Should check isDeviceSecure in shouldConfirmCredentials

The NPE is because createConfirmDeviceCredentialIntent returns a null
intent when it founds that user does not set a secure lock.
So the fix is we should check is the user set a secure lock screen as well.

The reason the crash only happens in multi-window flow because
we have null checking in
the normal flow (i.e. interceptWithConfirmCredentialsIfNeeded).
But I think we better check it explicitly.

Bug: 28716456
Change-Id: Ib204cd02c0007bd1df36908bb3b5254ec4ffb914

services/core/java/com/android/server/am/ActivityStarter.java

@@ -620,6 +620,10 @@ class ActivityStarter {
                 .getSystemService(Context.KEYGUARD_SERVICE);
         final Intent credential =
                 km.createConfirmDeviceCredentialIntent(null, null, userId);
+        // For safety, check null here in case users changed the setting after the checking.
+        if (credential == null) {
+            return;
+        }
         final ActivityRecord activityRecord = targetStack.topRunningActivityLocked();
         if (activityRecord != null) {
             final IIntentSender target = mService.getIntentSenderLocked(

services/core/java/com/android/server/am/UserController.java

@@ -1468,7 +1468,7 @@ final class UserController {
         }
         final KeyguardManager km = (KeyguardManager) mService.mContext
                 .getSystemService(KEYGUARD_SERVICE);
-        return km.isDeviceLocked(userId);
+        return km.isDeviceLocked(userId) && km.isDeviceSecure(userId);
     }
 
     boolean isLockScreenDisabled(@UserIdInt int userId) {