chrome/test/data/extensions/api_test/webrequest/on_action_ignored/extension_1/background.js

// Copyright 2018 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

var redirectIgnored = false;
var redirectedRequestId = null;

chrome.webRequest.onBeforeRequest.addListener(function(details) {
  if (details.url.includes('google.com') && details.type === 'main_frame') {
    redirectedRequestId = details.requestId;
    return {'redirectUrl': details.url.replace('google.com', 'example.com')};
  }
}, {urls: ['<all_urls>']}, ['blocking']);

chrome.webRequest.onActionIgnored.addListener(function(details) {
  if (details.requestId === redirectedRequestId &&
      details.action === 'redirect') {
    redirectIgnored = true;
  }
});

chrome.webRequest.onCompleted.addListener(function(details) {
  // onActionIgnored should have been received by the time onCompleted is
  // received for the request. Notify the browser whether the redirect was
  // successful.
  if (details.requestId === redirectedRequestId) {
    var message = redirectIgnored ? 'redirect_ignored' : 'redirect_successful';
    chrome.test.sendMessage(message);
    redirectIgnored = false;
    redirectedRequestId = null;
  }
}, {urls: ['<all_urls>']});

chrome.test.sendMessage('ready_1');