[Media Router] Custom Controls 4 - Implement details view WebUI

chrome/browser/resources/media_router/elements/route_details/extension_view_wrapper/extension_view_wrapper.js

+// Copyright 2017 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 the custom controller for a route using
+// extensionview.
+Polymer({
+  is: 'extension-view-wrapper',
+
+  properties: {
+    /**
+     * The route to show the custom controller for.
+     * @type {?media_router.Route|undefined}
+     */
+    route: {
+      type: Object,
+      observer: 'maybeLoadExtensionView_',
+    },
+
+    /**
+     * Whether the extension view is ready to be shown.
+     * @type {boolean}
+     */
+    isExtensionViewReady: {
+      type: Boolean,
+      value: false,
+      notify: true,
+    },
+  },
+
+  /**
+   * Called by Polymer when this module has loaded.
+   */
+  ready: function() {
+    this.maybeLoadExtensionView_();
+  },
+
+  /**
+   * Loads the custom controller if the controller path for the current route is
+   * valid.
+   */
+  maybeLoadExtensionView_: function() {
+    var extensionview = this.$['custom-controller'];
+
+    // Do nothing if the controller path doesn't exist or is already shown in
+    // the extension view.
+    if (!this.route || !this.route.customControllerPath ||
+        this.route.customControllerPath == extensionview.src) {
+      return;
+    }
+
+    var that = this;
+    extensionview.load(this.route.customControllerPath)
+        .then(
+            function() {
+              // Load was successful; show the custom controller.
+              that.isExtensionViewReady = true;
+            },
+            function() {
+              // Load was unsuccessful; fall back to default view.
+              that.isExtensionViewReady = false;
+            });
+  },
+});