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

/cc @brenca @codebytere 
atom/browser/osr/osr_web_contents_view.cc
void OffScreenWebContentsView::RenderViewCreated(
    content::RenderViewHost* host) {
  if (GetView())
    GetView()->InstallTransparency();
#if defined(OS_MACOSX)
  host->Send(new AtomViewMsg_Offscreen(host->GetRoutingID()));
#endif
}
void OffScreenWebContentsView::RenderViewReady() {}
void OffScreenWebContentsView::RenderViewHostChanged(
    content::RenderViewHost* old_host,
    content::RenderViewHost* new_host) {}
void OffScreenWebContentsView::SetOverscrollControllerEnabled(bool enabled) {}
#if defined(OS_MACOSX)
bool OffScreenWebContentsView::IsEventTracking() const {
  return false;
}
void OffScreenWebContentsView::CloseTabAfterEventTracking() {}