Got disabled in chromium 71 upgrade https://github.com/electron/electron/commit/798b2a3ffd55c477af6258f0afb71000c9f8ecde

/cc @brenca @codebytere 
atom/browser/osr/osr_web_contents_view.cc
auto* view = GetView();
  if (view != nullptr) {
    view->SetFrameRate(frame_rate);
  } else {
    frame_rate_ = frame_rate;
  }
}
int OffScreenWebContentsView::GetFrameRate() const {
  auto* view = GetView();
  if (view != nullptr) {
    return view->GetFrameRate();
  } else {
    return frame_rate_;
  }
}
OffScreenRenderWidgetHostView* OffScreenWebContentsView::GetView() const {
  if (web_contents_) {
    return static_cast<OffScreenRenderWidgetHostView*>(
        web_contents_->GetRenderViewHost()->GetWidget()->GetView());
  }
  return nullptr;
}
}