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

/cc @brenca @codebytere 
atom/browser/osr/osr_web_contents_view.cc
if (native_window_)
    native_window_->RemoveObserver(this);
  native_window_ = window;
  if (native_window_)
    native_window_->AddObserver(this);
  OnWindowResize();
}
void OffScreenWebContentsView::OnWindowResize() {
  
  if (GetView())
    GetView()->SetSize(GetSize());
}
void OffScreenWebContentsView::OnWindowClosed() {
  if (native_window_) {
    native_window_->RemoveObserver(this);
    native_window_ = nullptr;
  }
}
gfx::Size OffScreenWebContentsView::GetSize() {
  return native_window_ ? native_window_->GetSize() : gfx::Size();
}
#if !defined(OS_MACOSX)
gfx::NativeView OffScreenWebContentsView::GetNativeView() const {
  if (!native_window_)
    return gfx::NativeView();
  return native_window_->GetNativeView();
}
gfx::NativeView OffScreenWebContentsView::GetContentNativeView() const {