Introduce new basic playback test.

chrome/test/data/media/html/utils.js

+// Copyright (c) 2012 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.
+//
+// Miscellaneous utility functions for HTML media tests. Loading this script
+// should not modify the page in any way.
+//
+
+var QueryString = function () {
+  // Allows access to query parameters on the URL; e.g., given a URL like:
+  //
+  //    http://<url>/my.html?test=123&bob=123
+  //
+  // parameters can now be accessed via QueryString.test or QueryString.bob.
+  var params = {};
+
+  // RegEx to split out values by &.
+  var r = /([^&=]+)=?([^&]*)/g;
+
+  // Lambda function for decoding extracted match values. Replaces '+' with
+  // space so decodeURIComponent functions properly.
+  function d(s) { return decodeURIComponent(s.replace(/\+/g, ' ')); }
+
+  var match;
+  while (match = r.exec(window.location.search.substring(1)))
+    params[d(match[1])] = d(match[2]);
+
+  return params;
+} ();