Fix issue caused by updating list that references global scroll target.

chrome/browser/resources/settings/global_scroll_target_behavior.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.
 
 /**
  * @fileoverview |GlobalScrollTargetBehavior| allows an element to be aware of
  * the global scroll target. |scrollTarget| will be populated async by

[michaelpg, 2016/12/02 20:37:26]

update comments: when should scrollTarget be used vs activeTarget? and
activeRoute has to be overloaded

[hcarmona, 2016/12/05 15:57:35]

Done.

  * |setGlobalScrollTarget|. |setGlobalScrollTarget| should only be called once.
  */
 
 cr.define('settings', function() {
   var scrollTargetResolver = new PromiseResolver();
 
   /** @polymerBehavior */
-  var GlobalScrollTargetBehavior = {
+  var GlobalScrollTargetBehaviorImpl = {
     properties: {
       /**
        * Read only property for the scroll target.
        * @type {HTMLElement}
        */
       scrollTarget: {
         type: Object,
         readOnly: true,
       },
+
+      /**
+       * Property that is populated only when the |activeRoute| is navigated to.
+       * @type {HTMLElement}
+       */
+      activeTarget: {

[michaelpg, 2016/12/02 20:37:26]

nit: can you use something other than "active" for activeTarget/activeRoute?
because "activeTarget is populated only when the activeRoute is active" is
confusing.

[hcarmona, 2016/12/05 15:57:35]

Updated names to make it more apparent that these properties are intended for
subpages.

+        type: Object,
+        computed: 'getActiveTarget_(scrollTarget, active_)',
+      },
+
+      /**
+       * The route that controls the active state.
+       * @type {settings.Route}
+       * @private
+       */
+      activeRoute: Object,
+
+      /** Whether the |activeRoute| is active or not. */
+      active_: Boolean,
     },
 
     /** @override */
     attached: function() {
       scrollTargetResolver.promise.then(this._setScrollTarget.bind(this));
     },
+
+    currentRouteChanged: function(route) {
+      this.active_ = route == this.activeRoute;
+    },
+
+    getActiveTarget_: function(target, active) {
+      return active ? target : null;
+    },
   };
 
   /**
    * This should only be called once.
    * @param {HTMLElement} scrollTarget
    */
   var setGlobalScrollTarget = function(scrollTarget) {
     scrollTargetResolver.resolve(scrollTarget);
   };
 
   return {
-    GlobalScrollTargetBehavior: GlobalScrollTargetBehavior,
+    GlobalScrollTargetBehaviorImpl: GlobalScrollTargetBehaviorImpl,
     setGlobalScrollTarget: setGlobalScrollTarget,
+    scrollTargetResolver: scrollTargetResolver,
   };
 });
+
+// This is done to make the closure compiler happy: it needs fully qualified
+// names when specifying an array of behaviors.
+/** @polymerBehavior */
+settings.GlobalScrollTargetBehavior =
+      [settings.RouteObserverBehavior, settings.GlobalScrollTargetBehaviorImpl];

[michaelpg, 2016/12/02 20:37:26]

4-space indent

[hcarmona, 2016/12/05 15:57:35]

Done.