Add a browsertest suite for net predictor

chrome/test/data/predictor/fetch_cross_site.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.
+
+// This script file should be requested with the following query params:
+// subresourceHost: The base url of the embedded test server to request
+// subresources from.
+// numCORSResources: The number of resources to request (between 0 and 3).
+var queryString = window.location.search.substring(1);
+var vars = queryString.split("&");
+var parsedParams = {};
+vars.forEach(function(v) {
+  var key_value = v.split('=');
+  parsedParams[key_value[0]] = key_value[1];
+});
+var subresourceHost = parsedParams['subresourceHost'];
+var numCORSResources = parseInt(parsedParams['numCORSResources'], 10);
+var sendImmediately = parseInt(parsedParams['sendImmediately'], 10);
+var subresourceList = [
+  'predictor/empty.js',
+  'predictor/empty1.js',
+  'predictor/empty2.js',
+];
+var CORSSubresources = subresourceList.slice(0, numCORSResources);
+
+var numOK = 0;
+function logResponse(r) {
+  // Opaque responses are not necessarily network errors. We get them when we
+  // make cross origin requests with no-cors.
+  if (r.status == 200 || r.type == "opaque") {
+    numOK++;
+    if (numOK == numCORSResources) {
+      window.domAutomationController.send(true);
+    }
+  } else {
+    window.domAutomationController.send(false);
+  }
+}
+
+function startFetchesAndWaitForReply() {
+  CORSSubresources.forEach(function(r) {
+    fetch(subresourceHost + r, {mode: 'cors', method: 'get'}).then(logResponse);
+  });
+}
+
+if (sendImmediately) {
+  startFetchesAndWaitForReply();
+}