chrome.webRequest support for ExtensionSettings

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

Index: chrome/test/data/extensions/api_test/webrequest/policy_blocked/ref_remote_js.js
diff --git a/chrome/test/data/extensions/api_test/webrequest/policy_blocked/ref_remote_js.js b/chrome/test/data/extensions/api_test/webrequest/policy_blocked/ref_remote_js.js
new file mode 100644
index 0000000000000000000000000000000000000000..9b74cd6a7ba3ad6979c928580c689ea588f8739d
--- /dev/null
+++ b/chrome/test/data/extensions/api_test/webrequest/policy_blocked/ref_remote_js.js
@@ -0,0 +1,17 @@
+// Copyright (c) 2016 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 differentOriginLink = document.createElement('a');
+differentOriginLink.href = document.location.href;
+differentOriginLink.hostname = 'example2.com';
+var pathname = document.location.pathname;
+var root = pathname.split('/').slice(0,-1).join('/').toString();
+differentOriginLink.pathname = root + '/remote.js';
+var differentOriginScript = document.createElement('script');
+differentOriginScript.src = differentOriginLink.href;
+document.firstElementChild.appendChild(differentOriginScript);

[Devlin, 2017/05/25 20:38:32]

Why do we need this instead of just
var script = document.createElement('script');
script.src = <url>;
document.body.appendChild(script);
?

[nrpeter, 2017/05/26 02:46:52]

Each run, the embedded test server uses a different port. This code takes a url
like 
http://example.com:1234/extensions/api_test/webrequest/policy_blocked/ref_rem...
and turns it into
http://example2.com:1234/extensions/api_test/webrequest/policy_blocked/remote....

A script tag is then generated and set to the example2.com url which initiates a
web request with example.com as the initiator.

The main issues this approach solves is 1. Getting the port and 2. Not
hardcoding a path to the test file.
This could alternatively be done by using chrome.runtime to get the embedded
test server port from the content script. If you'd prefer me to use the
chrome.runtime approach please let me know and I'll rewrite it.

[Devlin, 2017/06/01 15:21:32]

var script = document.createElement('script');
script.src = 'http://example2.com:' + location.port +
             '/extensions/api_test/webrequest/policy_blocked/remote.js';
document.body.appendChild(script);

Would that work?

[nrpeter, 2017/06/06 21:42:07]

Switched to using your suggested implementation.

Note: This required changes to ref_remote_js.html since it didn't previously
declare a body. Without a declared body before the script execution
document.body will be null and we can't appendChild.