Disabled overscroll animation when the fullscreen app list feature is enabled.

ui/app_list/presenter/app_list_presenter_impl.h

Index: ui/app_list/presenter/app_list_presenter_impl.h
diff --git a/ui/app_list/presenter/app_list_presenter_impl.h b/ui/app_list/presenter/app_list_presenter_impl.h
index 4f1ee1bb2183303c61d307642f33e0800787580b..eb0d7e7964c37ca220259ce5e5d39c9114633d25 100644
--- a/ui/app_list/presenter/app_list_presenter_impl.h
+++ b/ui/app_list/presenter/app_list_presenter_impl.h
@@ -134,6 +134,9 @@ class APP_LIST_PRESENTER_EXPORT AppListPresenterImpl
   // Whether should schedule snap back animation.
   bool should_snap_back_ = false;
 
+  // Whether the fullscreen app list feature is enabled;
+  const bool is_fullscreen_app_list_enabled_;
+
   // The app list interface pointer; used for reporting visibility changes.
   mojom::AppListPtr app_list_;