* Electron Version 6.0.0-beta.12
* Operating System Windows 10 64 bit

Expected Behavior
webContents.print() should send print a job to the specified printer

Actual behavior
Nothing happens. Callback gets called much latter, for example on program exit.

To Reproduce
let print_options = { 
    silent: true,
    printBackground: true,
    deviceName: barcode_device_name 
}
print_window.webContents.print(print_options, (data) => {
    console.log(`print result: ${data}`)
})

Related to #17260
shell/browser/api/atom_api_web_contents.cc
bool proceed,
                                    bool* proceed_to_fire_unload) {
  if (type_ == Type::BROWSER_WINDOW || type_ == Type::OFF_SCREEN)
    *proceed_to_fire_unload = proceed;
  else
    *proceed_to_fire_unload = true;
}
void WebContents::SetContentsBounds(content::WebContents* source,
                                    const gfx::Rect& pos) {
  Emit("move", pos);
}
void WebContents::CloseContents(content::WebContents* source) {
  Emit("close");
  HideAutofillPopup();
  if (managed_web_contents())
    managed_web_contents()->GetView()->SetDelegate(nullptr);
  for (ExtendedWebContentsObserver& observer : observers_)
    observer.OnCloseContents();
}
void WebContents::ActivateContents(content::WebContents* source) {