Add Media Router route-details.

chrome/browser/resources/media_router/elements/route-details/route_details.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.
+
+// This Polymer element shows information from media that is currently cast
+// to a device.
+Polymer('route-details', {
+  publish: {
+    /**
+     * The route to show.
+     *
+     * @attribute route
+     * @type {media_router.Route}
+     * @default null
+     */
+    route: null,
+  },
+
+  /**
+   * Fires a back-click event. This is called when the back link is clicked.
+   */
+  back: function() {
+    this.fire('back-click');
+  },
+
+  /**
+   * Fires a close-route-click event. This is called when the button to close
+   * the current route is clicked.
+   */
+  closeRoute: function() {
+    this.fire('close-route-click', {route: this.route});
+  },
+});