* 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 only_dirty = false;
  FrameSubscriber::FrameCaptureCallback callback;
  args->GetNext(&only_dirty);
  if (!args->GetNext(&callback)) {
    args->ThrowError();
    return;
  }
  frame_subscriber_.reset(
      new FrameSubscriber(web_contents(), callback, only_dirty));
}
void WebContents::EndFrameSubscription() {
  frame_subscriber_.reset();
}
void WebContents::StartDrag(const mate::Dictionary& item,