Reland: 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.
+
+window.protectedOriginCount = 0;
+
+// Return messages to tell which URL requests are visible to the extension.
+chrome.webRequest.onBeforeRequest.addListener(function(details) {
+   if (details.url.indexOf('example2') != -1) {
+     ++window.protectedOriginCount;
+   }
+   if (details.url.indexOf('protected_url') != -1) {
+     chrome.test.sendMessage('protected_url');
+   }
+}, {urls: ['<all_urls>']}, []);
+
+chrome.test.sendMessage('ready');