MD Settings: Implementing a "no results" page.

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
  * 'settings-main' displays the selected settings page.
  */
 Polymer({
   is: 'settings-main',
@@ skipping 31 matching lines @@
      * @type {!{about: boolean, basic: boolean, advanced: boolean}}
      * @private
      */
     showPages_: {
       type: Object,
       value: function() {
         return {about: false, basic: false, advanced: false};
       },
     },
 
+    /** @private */
+    showNoResultsFound_: {
+      type: Boolean,
+      value: false,
+    },
+
     toolbarSpinnerActive: {
       type: Boolean,
       value: false,
       notify: true,
     },
   },
 
   /** @override */
   created: function() {
     /** @private {!PromiseResolver} */
     this.resolver_ = new PromiseResolver;
     settings.main.rendered = this.resolver_.promise;
   },
 
   /** @override */
-  ready: function() {
-    settings.getSearchManager().setCallback(function(isRunning) {
-      this.toolbarSpinnerActive = isRunning;
-    }.bind(this));
-  },
-
-  /** @override */
   attached: function() {
     document.addEventListener('toggle-advanced-page', function(e) {
       this.advancedToggleExpanded_ = e.detail;
       this.currentRoute = {
         page: this.advancedToggleExpanded_ ? 'advanced' : 'basic',
         section: '',
         subpage: [],
       };
     }.bind(this));
 
@@ skipping 63 matching lines @@
         this.currentRoute.subpage.length != 0) {
       this.currentRoute = {page: 'basic', section: '', subpage: [], url: ''};
     }
   },
 
   /**
    * @param {string} query
    */
   searchContents: function(query) {
     this.ensureInDefaultSearchPage_();
+    this.toolbarSpinnerActive = true;
 
     // Trigger rendering of the basic and advanced pages and search once ready.
-    // Even if those are already rendered, yield to the message loop before
-    // initiating searching.
     this.showPages_ = {about: false, basic: true, advanced: true};
+
     setTimeout(function() {
       settings.getSearchManager().search(
           query, assert(this.$$('settings-basic-page')));
     }.bind(this), 0);
     setTimeout(function() {
       settings.getSearchManager().search(
-          query, assert(this.$$('settings-advanced-page')));
+          query, assert(this.$$('settings-advanced-page'))).then(
+          function(request) {
+            if (!request.finished) {
+              // Nothing to do here. A previous search request was canceled
+              // because a new search request was issued before the first one
+              // completed.
+              return;
+            }
+
+            this.toolbarSpinnerActive = false;
+            this.showNoResultsFound_ =
+                !request.isSame('') && !request.didFindMatches();
+          }.bind(this));
     }.bind(this), 0);
   },
 });