mediator->VisibilityChanged(scrollbar, aVisible);
mediator->VisibilityChanged(aVisible);
nsGfxScrollFrameInner::SetScrollbarVisibility(nsIBox* aScrollbar, PRBool aVisible){  if (!aScrollbar)    return;  nsCOMPtr<nsIScrollbarFrame> scrollbar(do_QueryInterface(aScrollbar));  if (scrollbar) {    // See if we have a mediator.    nsCOMPtr<nsIScrollbarMediator> mediator;    scrollbar->GetScrollbarMediator(getter_AddRefs(mediator));    if (mediator) {      // Inform the mediator of the visibility change.      mediator->VisibilityChanged(scrollbar, aVisible);    }  }}