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: null
+     */
+    issue: null
+  },
+
+  /**
+   * Fires an issue-action-click event. This is called when an issue action
+   * is clicked.
+   *
+   * @param {!Event} event The event object.
+   * @param {Object} detail The details of the event.

[James Hawkins, 2015/04/06 21:52:48]

Can you use a well-typed typedef instead of Object?

[apacible, 2015/04/06 22:50:41]

I talked to jlklein@ about these @params; detail is denoted as 'Object' because
it isn't typed well for these events. While we can check its contents and be
more specific, we don't use detail here at all so he suggests we just keep this
as 'Object'.

+   * @param {!Element} sender Reference to clicked node.
+   */
+  onClickAction: function(event, detail, sender) {
+    this.fire('issue-action-click', {
+      id: this.issue.id,
+      actionType: parseInt(sender.title),
+      helpURL: this.issue.helpURL
+    });
+  }
+});