Add cr-toggle-button to Chrome

ui/webui/resources/cr_elements/cr_events/cr-events.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-events` provides helpers for handling events in Chrome Polymer elements.
+ *
+ * Example:
+ *
+ *    <cr-events id="events"></cr-events>
+ *
+ * Usage:
+ *
+ *    this.$.events.forward(this.$.element, ['change']);
+ *
+ * @element cr-events
+ */
+Polymer({
+  /**
+   * Sets up an element to forward events across the shadow boundary, for events
+   * which normally stop at the root node (see http://goo.gl/WGMO9x).
+   * @param {!HTMLElement} element The element to forward events from.
+   * @param {!Array.<string>} events The events to forward.
+   */
+  forward: function(element, events) {
+    for (var i = 0; i < events.length; i++)
+      element.addEventListener(events[i], this.forwardEvent_);
+  },
+
+  /**

[James Hawkins, 2015/02/09 22:24:34]

nit: Double-blank lines above JSDoc blocks (though I don't think you need one
above line 20).

[michaelpg, 2015/02/09 22:40:04]

Hmm I haven't seen that style in other web ui, where is this coming from?

[James Hawkins, 2015/02/09 22:46:23]

I forgot this isn't in the JS style guide, but the Closure extension to the
style guide [1].

Just chatted with Jeremy, and for the sake of conforming to the compiler (once
we implement support) and the linter (which we should also add support for), we
should stick to the Closure style guide as well as JS style guide.

[1]
https://sites.google.com/a/google.com/closure/documentation/closure-style-guide

[michaelpg, 2015/02/09 23:08:31]

Done.

[Dan Beam, 2015/02/10 00:23:38]

fwiw: I'd discourage this for consistency with other code, but we're rewriting
it all anyways and parts of webui already do the \n\n thing

+   * Forwards events that don't automatically cross the shadow boundary
+   * if the event should bubble.
+   * @param {!Event} e The event to forward.
+   * @param {*} detail Data passed when initializing the event.
+   * @param {Node=} sender Node that declared the handler.
+   * @private
+   */
+  forwardEvent_: function(e, detail, sender) {
+    if (!e.bubbles)
+      return;
+
+    var node = e.path[e.path.length - 1];
+    if (node instanceof ShadowRoot) {
+      // Forward the event to the shadow host.
+      e.stopPropagation();
+      node.host.fire(e.type, detail, node.host, true, e.cancelable);
+    }
+  },
+});