[Media Router] Add a supports_web_ui_controller attribute to MediaRoute

chrome/browser/resources/media_router/elements/media_router_container/media_router_container.js

Index: chrome/browser/resources/media_router/elements/media_router_container/media_router_container.js
diff --git a/chrome/browser/resources/media_router/elements/media_router_container/media_router_container.js b/chrome/browser/resources/media_router/elements/media_router_container/media_router_container.js
index 155bc82031fd8bf9f4699defaae97426f2c577b6..ca53dd5c06ce7d04acf7214f816fecdc83a03406 100644
--- a/chrome/browser/resources/media_router/elements/media_router_container/media_router_container.js
+++ b/chrome/browser/resources/media_router/elements/media_router_container/media_router_container.js
@@ -392,9 +392,9 @@ Polymer({
     /**
      * Whether the WebUI route controls should be shown instead of the
      * extensionview in the route details view.
-     * @type {boolean}
+     * @private {boolean}
      */
-    useWebUiRouteControls: {
+    useWebUiRouteControls_: {
       type: Boolean,
       value: false,
     },
@@ -416,6 +416,16 @@ Polymer({
       type: Boolean,
       value: false,
     },
+
+    /**
+     * Whether the WebUI route controls are available for use. Used for updating
+     * the value of |useWebUiRouteControls_|.
+     * @type {boolean}
+     */
+    webUiRouteControlsAvailable: {
+      type: Boolean,
+      value: false,
+    }
   },
 
   behaviors: [
@@ -1825,7 +1835,7 @@ Polymer({
    * from route details view to the sink list view.
    */
   onRouteControllerInvalidated: function() {
-    if (this.useWebUiRouteControls &&
+    if (this.useWebUiRouteControls_ &&
         this.currentView_ == media_router.MediaRouterView.ROUTE_DETAILS) {
       this.currentRoute_ = null;
       this.showSinkList_();
@@ -2386,7 +2396,9 @@ Polymer({
   showRouteDetails_: function(route) {
     this.currentRoute_ = route;
     this.currentView_ = media_router.MediaRouterView.ROUTE_DETAILS;
-    if (this.useWebUiRouteControls) {
+    this.useWebUiRouteControls_ =
+        this.webUiRouteControlsAvailable && route.supportsWebUiController;
+    if (this.useWebUiRouteControls_) {
       media_router.browserApi.onMediaControllerAvailable(route.id);
     }
     if (this.$$('route-details')) {