Add tests for webRequest events and frame unload

chrome/test/data/extensions/api_test/webrequest/test_unload.js

+// Copyright 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.
+
+// Returns a URL of a page that generates a response after waiting for a long
+// while. You should try to cancel the request as soon as reasonably possible.

[battre, 2016/05/23 11:17:07]

The comment "You should try..." does not seem to belong here in my opinion.
Maybe there should be file level comment on what is tested here and how.

[robwu, 2016/05/23 11:51:03]

Reworded and added a small file-level comment.

+// |hostname| can be set to make sure that the frame is created in a new process
+// if site isolation is enabled.
+function getSlowURL(hostname) {
+  // Waiting for 10 seconds should be more than sufficient.
+  return getServerURL('slow?10', hostname);
+}
+
+// Get the URL of a page that inserts a frame with the given URL upon load.
+function getPageWithFrame(frameUrl, hostname) {
+  return getServerURL('extensions/api_test/webrequest/unload/load_frame.html?' +
+      encodeURIComponent(frameUrl), hostname);
+}
+
+// Invokes |callback| when when the onSendHeaders event occurs. When used with
+// getNewSlowURL(), this signals when the request has been processed and that

[battre, 2016/05/23 11:17:07]

I guess you have renamed getNewSlowURL to getSlowURL.

[robwu, 2016/05/23 11:51:03]

Done.

+// there won't be any webRequest events for a long while.
+// This allows the test to deterministically cancel the request, which should
+// trigger onErrorOccurred.
+function waitUntilSendHeaders(type, url, callback) {
+  chrome.test.assertTrue(/^https?:.+\/slow\?/.test(url),
+      'Must be a slow URL, but was ' + url);
+
+  chrome.webRequest.onSendHeaders.addListener(function listener() {
+    chrome.webRequest.onSendHeaders.removeListener(listener);
+    callback();
+  }, {
+    types: [type],
+    urls: [url],
+  });
+}
+
+(function() {
+  // Load the actual test file.
+  var id = location.search.slice(1);
+  chrome.test.assertTrue(/^\d+$/.test(id),
+      'Page URL should end with digits, but got ' + id);
+  console.log('Running test_unload ' + id);
+
+  var s = document.createElement('script');
+  // test_unload1.js, test_unload2.js, ..., etc.
+  // These tests are in separate files to make sure that the tests are
+  // independent of each other. If they were put in one file, then the tabId
+  // of one test would depend on the number of tabs from the previous tests.
+  s.src = 'test_unload' + id + '.js';
+  s.onerror = function() {
+    chrome.test.fail('Failed to load test ' + s.src);
+  };
+
+  // At the next test, a call to RunExtensionSubtest causes the extension to
+  // reload. As a result, all extension pages are closed. If the extension page
+  // was the only tab in the browser, then the browser would exit and cause the
+  // test to end too early. To avoid this problem, create an extra non-extension
+  // tab before starting tests.
+  chrome.tabs.create({
+    url: 'data:,'
+  }, function() {
+    document.body.appendChild(s);
+  });
+})();