[Search] Make the text swoosh away off the screen when the user taps the opt-in link.

chrome/browser/resources/contextual_search/promo.js

 /* Copyright 2014 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.
-   TODO(mathp): Add some JS here.
 */
+
+/**
+ * On load, registers the handler to add the 'fadeout' class to the container
+ * element in order to fade it out.
+ */
+window.onload = function() {
+  $('optin-label').addEventListener('click', function() {
+    $('container').classList.add('fadeout');

[pedro (no code reviews), 2014/08/11 21:38:02]

Nit: if you use names describing the function (hide/dismiss) instead of the
implementation (slide/fadeout) you won't have to rename it every time the
animation specs change :)

[Mathieu, 2014/08/12 12:39:46]

Done.

+  });
+};