chromium/chrome/test/data/extensions/api_test/offscreen/basic_document_management/offscreen.js

// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

chrome.runtime.onMessage.addListener((msg, sender, sendResponse) => {
  sendResponse({msg, reply: 'offscreen reply'});
});