[Media Router] Consistently refer to issue's learn more help page by ID.

extensions/renderer/resources/media_router_bindings.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.
 
 var mediaRouter;
 
 define('media_router_bindings', [
     'mojo/public/js/bindings',
     'mojo/public/js/core',
     'content/public/renderer/frame_service_registry',
@@ skipping 335 matching lines @@
     var secondaryActions = (issue.secondaryActions || []).map(function(e) {
       return issueActionToMojo_(e);
     });
     this.service_.onIssue(new mediaRouterMojom.Issue({
       'route_id': issue.routeId,
       'severity': issueSeverityToMojo_(issue.severity),
       'title': issue.title,
       'message': issue.message,
       'default_action': issueActionToMojo_(issue.defaultAction),
       'secondary_actions': secondaryActions,
-      'help_url': issue.helpUrl,
+      'help_page_id': issue.helpPageId,
       'is_blocking': issue.isBlocking
     }));
   };
 
   /**
    * Called by the provider manager when the set of active routes
    * has been updated.
    * @param {!Array<MediaRoute>} routes The active set of media routes.
    * @param {string=} opt_sourceUrn The sourceUrn associated with this route
    *     query. This parameter is optional and can be empty.
@@ skipping 447 matching lines @@
   };
 
   mediaRouter = new MediaRouter(connector.bindHandleToProxy(
       serviceProvider.connectToService(
           mediaRouterMojom.MediaRouter.name),
       mediaRouterMojom.MediaRouter));
 
   return mediaRouter;
 });