Refine Activity.isVisibleForAutofill() to let it more readable

Bug: 196929439
Test: manual. install app and the app doesn't crash.
Test: atest CtsAutoFillServiceTestCases
Change-Id: Iacda5f27a306b258b46aa71d7ff4f0b2492983e9

core/java/android/app/Activity.java

@@ -8411,7 +8411,7 @@ public class Activity extends ContextThemeWrapper
      * @hide
      */
     public final boolean isVisibleForAutofill() {
-        return mStopped;
+        return !mStopped;
     }
 
     /**

core/java/android/view/autofill/AutofillClientController.java

@@ -324,7 +324,7 @@ public final class AutofillClientController implements AutofillManager.AutofillC
 
     @Override
     public boolean autofillClientIsVisibleForAutofill() {
-        return !mActivity.isVisibleForAutofill();
+        return mActivity.isVisibleForAutofill();
     }
 
     @Override