Revert of chrome.webRequest support for ExtensionSettings

chrome/test/data/extensions/api_test/webrequest/policy_blocked/background.js

-// Copyright 2017 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.
-
-// Return messages to tell which URL requests are visible to the extension.
-chrome.webRequest.onBeforeRequest.addListener(function(details) {
-   if (details.url.indexOf('example2') != -1) {
-     chrome.test.sendMessage('protected_origin');
-   }
-   if (details.url.indexOf('protected_url') != -1) {
-     chrome.test.sendMessage('protected_url');
-   }
-}, {urls: ['<all_urls>']}, []);