Update cr-network-list iron-list when contents change

ui/webui/resources/cr_elements/network/cr_network_list.js

Index: ui/webui/resources/cr_elements/network/cr_network_list.js
diff --git a/ui/webui/resources/cr_elements/network/cr_network_list.js b/ui/webui/resources/cr_elements/network/cr_network_list.js
index 43af5690d0bcbf61b95f4fe59fb2c64a5ac0585b..e1ded9a75368a2ddc21ea7a51f96c61d2316f75d 100644
--- a/ui/webui/resources/cr_elements/network/cr_network_list.js
+++ b/ui/webui/resources/cr_elements/network/cr_network_list.js
@@ -70,11 +70,18 @@ Polymer({
 
   behaviors: [CrScrollableBehavior],
 
+  observers: ['listChanged_(networks, customItems)'],
+
   /** @private */
   maxHeightChanged_: function() {
     this.$.container.style.maxHeight = this.maxHeight + 'px';
   },
 
+  /** @private */
+  listChanged_: function() {
+    this.updateScrollableContents();
+  },
+
   /**
    * Returns a combined list of networks and custom items.
    * @return {!Array<!CrNetworkList.CrNetworkListItemType>}