Fix crash in ChooseLockPassworkFragment. am: f958f2e14e am: 773a2ab217

am: 6ffe36cf79

Change-Id: I6792e6ac9bd209c7e2dc8b20a5173bb01ed788bc

src/com/android/settings/ChooseLockPassword.java

@@ -900,6 +900,9 @@ public class ChooseLockPassword extends SettingsActivity {
 
             @Override
             public void handleMessage(Message msg) {
+                if (getActivity() == null) {
+                    return;
+                }
                 if (msg.what == ON_TEXT_CHANGED) {
                     updateUi();
                 }