Fix flaky WindowTokenClientControllerTest

Create a new instance for testing instead of using the app's real
instance.

The failure only happens once and likely to be an isolated one. Likely to be a side effect of using the application's real instance.

Fix: 293161156
Test: atest FrameworksCoreTests:WindowTokenClientControllerTest
Change-Id: I77f0e34066c61f1f5aaf95551e6d58cf96d112b4

core/java/android/window/WindowTokenClientController.java

@@ -73,6 +73,12 @@ public class WindowTokenClientController {
         }
     }
 
+    /** Creates a new instance for test only. */
+    @VisibleForTesting
+    public static WindowTokenClientController createInstanceForTesting() {
+        return new WindowTokenClientController();
+    }
+
     private WindowTokenClientController() {}
 
     /**

core/tests/coretests/src/android/window/WindowTokenClientControllerTest.java

@@ -76,7 +76,7 @@ public class WindowTokenClientControllerTest {
         mOriginalWindowManagerService = WindowManagerGlobal.getWindowManagerService();
         WindowManagerGlobal.overrideWindowManagerServiceForTesting(mWindowManagerService);
         doReturn(mClientToken).when(mWindowTokenClient).asBinder();
-        mController = spy(WindowTokenClientController.getInstance());
+        mController = spy(WindowTokenClientController.createInstanceForTesting());
     }
 
     @After