Add cr-toggle-button to Chrome

ui/webui/resources/custom_elements/cr/toggle-button/cr-toggle-button.js

+/* 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-toggle-button` provides a switch the user can toggle on or off by
+ * tapping or by dragging. Wraps a `paper-toggle-button`.
+ *
+ * Example:
+ *
+ *    <cr-toggle-button></cr-toggle-button>
+ *
+ * @element cr-toggle-button
+ */
+Polymer({
+  publish: {
+    /**
+     * Gets or sets the state. `true` is checked and `false` is unchecked.
+     *
+     * @attribute checked
+     * @type boolean
+     * @default false
+     */
+    checked: {
+      value: false,
+      reflect: true,
+    },
+
+    /**
+     * If true, the toggle button is disabled.
+     *
+     * @attribute disabled
+     * @type boolean
+     * @default false
+     */
+    disabled: {
+      value: false,
+      reflect: true,
+    },
+  },

[stevenjb, 2015/02/05 23:36:21]

It does seem a little tedious to have to re-publish and re-document these from
paper-toggle-button. Is there a way to make closure happy without copying the
comment blocks? At minimum we should indicate that these are being forwarded and
not introduced.

[Jeremy Klein, 2015/02/05 23:42:11]

+1. This is a lot of code for a really thin wrapper, but we did see this coming
:-(. Unfortunately, without a clear inheritance story, I don't see a way to
reduce this boilerplate. Indicating that they're just delegates seems
reasonable, though. I wonder if using mixins will eventually be the 0.8 way to
do things like this.

+
+  ready: function() {
+    this.$['toggle-button'].addEventListener('change',
+                                             this.$.util.forwardEvent);
+  },
+});