Implement md-settings network lists.

ui/webui/resources/cr_elements/cr_expand_button/cr_expand_button.js

Index: ui/webui/resources/cr_elements/cr_expand_button/cr_expand_button.js
diff --git a/ui/webui/resources/cr_elements/cr_expand_button/cr_expand_button.js b/ui/webui/resources/cr_elements/cr_expand_button/cr_expand_button.js
new file mode 100644
index 0000000000000000000000000000000000000000..730f8d8a80c04244ce72cf65dcff84a0805e9402
--- /dev/null
+++ b/ui/webui/resources/cr_elements/cr_expand_button/cr_expand_button.js
@@ -0,0 +1,46 @@
+// Copyright 2015 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
+ * 'cr-expand-button' is a chrome-specific wrapper around paper-button that
+ * toggles between an opened (expanded) and closed state.
+ *
+ * Example:
+ *
+ *    <cr-expand-button expanded={{sectionIsExpanded}}></cr-expand-button>

[michaelpg, 2015/04/23 02:16:29]

nit: need "" around the {{}} in the example

[stevenjb, 2015/04/24 01:25:26]

Done.

+ *
+ * @group Chrome Elements
+ * @element cr-expand-button
+ */
+Polymer('cr-expand-button', {
+  publish: {
+    /**
+     * If true, the button is in the expanded state and will show the
+     * 'expand-less' icon. If false, the button shows the 'expand-more' icon.
+     *
+     * @attribute expanded
+     * @type boolean
+     * @default false
+     */
+    expanded: false,
+
+    /**
+     * If true, the button will be disabled and greyed out.
+     *
+     * @attribute disabled
+     * @type boolean
+     * @default false
+     */
+    disabled: {value: false, reflect: true},
+  },
+
+  /**
+   * Event triggered when the expand button is clicked. Updates the expand
+   * property.
+   */
+  toggleExpanded: function() {
+    this.expanded = !this.expanded;
+  },
+});