void Shell::OnModalWindowRemoved(aura::Window* removed) {
  RootWindowControllerList controllers = GetAllRootWindowControllers();
  bool activated = false;
  for (RootWindowControllerList::iterator iter = controllers.begin();
       iter != controllers.end() && !activated; ++iter) {
    activated = (*iter)->GetSystemModalLayoutManager(removed)->
        ActivateNextModalWindow();
  }
  if (!activated) {
    RemovePreTargetHandler(modality_filter_.get());
    modality_filter_.reset();
    for (RootWindowControllerList::iterator iter = controllers.begin();
         iter != controllers.end(); ++iter)
      (*iter)->GetSystemModalLayoutManager(removed)->DestroyModalBackground();
  }
}

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