cancel overlay-scrollbar hover state when moving pointer out of window for ChromeOS

cc/trees/layer_tree_host_impl.cc

Index: cc/trees/layer_tree_host_impl.cc
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index 4aa0886dfb80d80425acf157f5d0e7d8daf1e872..d6c95117dd2bb45c54703c68b291ddc95097a28e 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -3266,6 +3266,16 @@ void LayerTreeHostImpl::MouseMoveAt(const gfx::Point& viewport_point) {
                                          active_tree_->device_scale_factor());
 }
 
+void LayerTreeHostImpl::MouseLeave() {
+  ScrollbarAnimationController* animation_controller =
+      ScrollbarAnimationControllerForId(
+        scroll_layer_id_when_mouse_over_scrollbar_);
+
+  if (animation_controller) {
+    animation_controller->DidMouseLeave();
+  }
+}
+
 void LayerTreeHostImpl::HandleMouseOverScrollbar(LayerImpl* layer_impl) {
   int new_id = Layer::INVALID_ID;
   if (layer_impl && layer_impl->ToScrollbarLayer())