Reland: chrome.webRequest support for ExtensionSettings

chrome/test/data/extensions/api_test/webrequest/policy_blocked/ref_remote_js.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.
+
+// Injects a script tag with a source based on the current URL. The script
+// however will be served from a different domain (example2.com) and target a
+// different file which is blank. This lets us make a request with an initiator
+// of example.com and a URL of example2.com.
+var script = document.createElement('script');
+script.src = 'http://example2.com:' + location.port + '/empty.html';
+document.body.appendChild(script);