Settings Router Refactor: Kill settings-router.

chrome/browser/resources/settings/route.js

 // Copyright 2016 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.
 
 cr.define('settings', function() {
   /**
    * Class for navigable routes. May only be instantiated within this file.
    * @constructor
    * @param {string} path
    * @private
@@ skipping 252 matching lines @@
 </if>
 
   var routeObservers_ = new Set();
 
   /** @polymerBehavior */
   var RouteObserverBehavior = {
     /** @override */
     attached: function() {
       assert(!routeObservers_.has(this));
       routeObservers_.add(this);
+
+      // Emulating Polymer data bindings, the observer is called when the
+      // element starts observing the route.
+      this.currentRouteChanged(currentRoute_, undefined);
     },
 
     /** @override */
     detached: function() {
       assert(routeObservers_.delete(this));
     },
 
     /** @abstract */
     currentRouteChanged: assertNotReached,
   };
@@ skipping 35 matching lines @@
       window.history.pushState(undefined, '', Route.BASIC.path);
     }
   })();
 
   /**
    * Helper function to set the current route and notify all observers.
    * @param {!settings.Route} route
    * @param {!URLSearchParams} queryParameters
    */
   var setCurrentRoute = function(route, queryParameters) {
+    var oldRoute = currentRoute_;
     currentRoute_ = route;
     currentQueryParameters_ = queryParameters;
     for (var observer of routeObservers_)
-      observer.currentRouteChanged();
+      observer.currentRouteChanged(currentRoute_, oldRoute);
   };
 
   /** @return {!settings.Route} */
   var getCurrentRoute = function() { return currentRoute_; };
 
   /** @return {!URLSearchParams} */
   var getQueryParameters = function() {
     return new URLSearchParams(currentQueryParameters_);  // Defensive copy.
   };
 
@@ skipping 30 matching lines @@
 
   return {
     Route: Route,
     RouteObserverBehavior: RouteObserverBehavior,
     getRouteForPath: getRouteForPath,
     getCurrentRoute: getCurrentRoute,
     getQueryParameters: getQueryParameters,
     navigateTo: navigateTo,
   };
 });