Add Media Router issue-banner.

chrome/browser/resources/media_router/elements/issue_banner/issue_banner.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.
+
+Polymer('issue-banner', {
+  publish: {
+    /**
+     * The issue to show.
+     *
+     * @attribute issue
+     * @type {media_router.Issue}
+     * @default: undefined
+     */
+    issue: undefined

[Jeremy Klein, 2015/04/06 18:49:58]

nit: The convention I've seen for this has been to use null instead of
undefined. I'm not entirely sure why, but it seems like we should keep that for
consistency unless you have a specific reason to use undefined.

[apacible, 2015/04/06 21:02:44]

Done.

+  },
+
+  created: function() {
+    this.issue = undefined;

[Jeremy Klein, 2015/04/06 18:49:57]

You don't need to do this unless you're actually initializing this to an object.

[apacible, 2015/04/06 21:02:43]

Done.

+  },
+
+  onClickAction: function(event, detail, sender) {

[Jeremy Klein, 2015/04/06 18:49:58]

nit: JSDocs

[apacible, 2015/04/06 21:02:44]

Added.

+    this.fire('issue-action-click', {
+      id: this.issue.id,
+      actionType: parseInt(sender.title),
+      helpURL: this.issue.helpURL
+    });
+  }
+});