Lots of small fixes to help wire things together for the 0.8 upgrade.

chrome/browser/resources/settings/settings_main/settings_main.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.
 
 /**
  * @fileoverview
  * 'cr-settings-main' displays the selected settings page.
  *
  * Example:
  *
@@ skipping 14 matching lines @@
      *
      * @type {?CrSettingsPrefsElement}
      */
     prefs: {
       type: Object,
       notify: true,
     },
 
     /**
      * Pages that may be shown.
-     * @type {?Array<!HTMLElement>}
+     * @type {!Array<!HTMLElement>}
      */
-    pages: Array,
+    pages: {
+      type: Array,
+      value: function() { return []; },
+      notify: true,
+      readOnly: true,
+    },
 
     /**
      * Currently selected page.
      * @type {?HTMLElement}
      */
     selectedPage: {
       type: Object,
       notify: true,
     },
 
     /**
      * ID of the currently selected page.
      */
     selectedPageId: {
       type: String,
       notify: true,
-      observe: 'selectedPageIdChanged_',
+      value: '',
+      observer: 'selectedPageIdChanged_',
     },
   },
 
   /** @override */
   ready: function() {
     var observer = new MutationObserver(this.pageContainerUpdated_.bind(this));
     observer.observe(this.$.pageContainer,
                      /** @type {MutationObserverInit} */ {
                        childList: true,
                      });
@@ skipping 12 matching lines @@
    * We observe $.pageContainer.on-iron-select instead of using data binding
    * for two reasons:
    * 1) We need to exclude subpages
    * 2) There is a bug with data binding or our useage of it here causing
    *    this.selectedPage to get set to the index of $.pageContainer instead of
    *    the valueattr identifier (PAGE_ID). TODO(stevenjb/jlklien): Investigate
    *    fixing this and using filters once we switch to Polymer 0.8.
    * @private
    */
   onIronSelect_: function(event) {
-    if (event.target != this.$.pageContainer || !event.detail.isSelected ||
-        event.detail.item.subpage) {
+    if (event.target != this.$.pageContainer || event.detail.item.subpage) {
       return;
     }
     this.selectedPageId = event.detail.item.PAGE_ID;
   },
 
   /**
    * If no page is selected, selects the first page. This happens on load and
    * when a selected page is removed.
    * @private
    */
   ensureSelection_: function() {
     if (!this.pages.length)
       return;
     if (this.selectedPageId == '')
       this.selectedPageId = this.pages[0].PAGE_ID;
   },
 
   /**
    * Updates the list of pages using the pages in iron-pages.
    * @private
    */
   pageContainerUpdated_: function() {
-    this.pages = this.$.pageContainer.items.filter(function(item) {
+    this._setPages(this.$.pageContainer.items.filter(function(item) {
       return !item.subpage;
-    });
+    }));
     this.ensureSelection_();
   },
 });