[Mac] Update fullscreen state when window is fullscreened natively.

apps/app_window.h

Index: apps/app_window.h
diff --git a/apps/app_window.h b/apps/app_window.h
index 3fd57570cf43126dd61ab71ef32c5a8e247a482c..907f1356e3b39f4f37aef9aa19773bdafd10512d 100644
--- a/apps/app_window.h
+++ b/apps/app_window.h
@@ -337,6 +337,10 @@ class AppWindow : public content::NotificationObserver,
     return app_window_contents_.get();
   }
 
+  int fullscreen_types_for_test() {
+    return fullscreen_types_;
+  }
+
   // Set whether the window should stay above other windows which are not
   // configured to be always-on-top.
   void SetAlwaysOnTop(bool always_on_top);