MD Settings: Deflake attempt for CrSettingsPrivacyPageTest.PrivacyPage.

chrome/test/data/webui/settings/test_util.js

Index: chrome/test/data/webui/settings/test_util.js
diff --git a/chrome/test/data/webui/settings/test_util.js b/chrome/test/data/webui/settings/test_util.js
new file mode 100644
index 0000000000000000000000000000000000000000..72a1cced91f1837b4dce72b4bf43ce6930155e20
--- /dev/null
+++ b/chrome/test/data/webui/settings/test_util.js
@@ -0,0 +1,43 @@
+// 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.
+
+

[Dan Beam, 2016/09/15 18:17:08]

nit: remove extra \n

[dpapad, 2016/09/15 18:52:12]

Done.

+cr.define('test_util', function() {
+  /**
+   * Observes an HTML attribute and fires a promise when it changes.
+   * @param {!HTMLElement} target
+   * @param {string} attributeName
+   * @return {!Promise}
+   */
+  function whenAttributeChanges(target, attributeName) {

[Dan Beam, 2016/09/15 18:17:08]

whenAttributeIs(target, attributeName, attributeValue) {
  function done() { return target[attributeName] === attributeValue; }

  return done() ? Promise.resolve() : new Promise(function(resolve) {
    new MutationObserver(function(mutations, observer) {
      for (var mutation of mutations) {
        if (mutation.attributeName == attributeName && done()) {
          observer.disconnect();
          resolve();
          return;
        }
      }
    }).observe(target, {...});
  });

[dpapad, 2016/09/15 18:52:12]

Done.

+    return new Promise(function(resolve, reject) {
+      var observer = new MutationObserver(function(mutations) {
+        assertEquals(1, mutations.length);
+        assertEquals('attributes', mutations[0].type);
+        assertEquals(attributeName, mutations[0].attributeName);
+        observer.disconnect();
+        resolve();
+      });
+      observer.observe(
+          target, {attributes: true, childList: false, characterData: false});
+    });
+  }
+
+  /**
+   * Converts an event occurrence to a promise.
+   * @param {string} eventType
+   * @param {!HTMLElement} target
+   * @return {!Promise} A promise firing once the event occurs.
+   */
+  function eventToPromise(eventType, target) {
+    return new Promise(function(resolve, reject) {
+      target.addEventListener(eventType, resolve);
+    });
+  }
+
+  return {
+    eventToPromise: eventToPromise,
+    whenAttributeChanges: whenAttributeChanges,
+  };
+});