Removed old media-internals page and rewrote it.

content/browser/resources/media/new/collapse.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.
+
+
+/**
+ * @fileoverview Sets up the event handlers for the collapsing containers
+ */
+
+(function () {
+  "use strict";
+  var allCollapseDivs = document.querySelectorAll('.collapse');
+  (Array.prototype.slice.call(allCollapseDivs)).forEach(function (elem) {
+    // find the header for the div, because we only want to trigger on that
+    var header = elem.querySelector("h2");
+    header.onclick = function () {
+      var wasOpen = elem.className.indexOf("open") !== -1;
+
+      if (wasOpen) {
+        elem.className = "collapse closed";
+      } else {
+        elem.className = "collapse open";
+      }
+    };
+  });
+
+}());