When exiting lock task require authentication

When exiting lock task with screen locking on make sure to notify
that the credentials need to be entered again.

Bug: 16496374
Change-Id: I891a8a8a04a67aa70eba8ea78bd585ad0dd17808
diff --git a/services/core/java/com/android/server/am/ActivityStackSupervisor.java b/services/core/java/com/android/server/am/ActivityStackSupervisor.java
index 52ace54..b4e66c1 100644
--- a/services/core/java/com/android/server/am/ActivityStackSupervisor.java
+++ b/services/core/java/com/android/server/am/ActivityStackSupervisor.java
@@ -97,6 +97,7 @@
 import com.android.internal.app.IVoiceInteractor;
 import com.android.internal.os.TransferPipe;
 import com.android.internal.statusbar.IStatusBarService;
+import com.android.internal.widget.LockPatternUtils;
 import com.android.server.LocalServices;
 import com.android.server.am.ActivityStack.ActivityState;
 import com.android.server.wm.WindowManagerService;
@@ -3327,6 +3328,8 @@
                             if (!mLockTaskIsLocked && shouldLockKeyguard) {
                                 mWindowManager.lockNow(null);
                                 mWindowManager.dismissKeyguard();
+                                new LockPatternUtils(mService.mContext)
+                                        .requireCredentialEntry(UserHandle.USER_ALL);
                             }
                         } catch (SettingNotFoundException e) {
                             // No setting, don't lock.