Disable overlay scrollbars in Blink when hidden by the compositor.

cc/layers/layer.cc

Index: cc/layers/layer.cc
diff --git a/cc/layers/layer.cc b/cc/layers/layer.cc
index 517a1c6a634511b8774f01d285dcac06f1038d5d..5d17c61c978da3eff0f1566f8f9fbd19088a39c3 100644
--- a/cc/layers/layer.cc
+++ b/cc/layers/layer.cc
@@ -1611,6 +1611,11 @@ void Layer::SetMayContainVideo(bool yes) {
   SetNeedsPushProperties();
 }
 
+void Layer::SetScrollbarsHiddenFromImplSide(bool hidden) {
+  if (inputs_.client)
+    inputs_.client->didChangeScrollbarsHidden(hidden);
+}
+
 bool Layer::FilterIsAnimating() const {
   return GetAnimationHost()->IsAnimatingFilterProperty(
       element_id(), GetElementTypeForAnimation());