Relanding: MD Settings: Adding some unit tests for <settings-main>.

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 188 matching lines @@
   /**
    * Navigates to the default search page (if necessary).
    * @private
    */
   ensureInDefaultSearchPage_: function() {
     settings.navigateTo(settings.Route.BASIC);
   },
 
   /**
    * @param {string} query
+   * @return {!Promise} A promise indicating that searching finished.
    */
   searchContents: function(query) {
     this.ensureInDefaultSearchPage_();
     this.toolbarSpinnerActive = true;
 
     // Trigger rendering of the basic and advanced pages and search once ready.
     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'))).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;
-            }
+    return new Promise(function(resolve, reject) {
+      setTimeout(function() {
+        var whenSearchDone = settings.getSearchManager().search(
+            query, assert(this.$$('settings-basic-page')));
+        assert(
+            whenSearchDone ===
+                settings.getSearchManager().search(
+                    query, assert(this.$$('settings-advanced-page'))));
 
-            this.toolbarSpinnerActive = false;
-            this.showNoResultsFound_ =
-                !request.isSame('') && !request.didFindMatches();
-          }.bind(this));
-    }.bind(this), 0);
+        whenSearchDone.then(function(request) {
+          resolve();
+          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);
+    }.bind(this));
   },
 
   /**
    * @param {(boolean|undefined)} visibility
    * @return {boolean} True unless visibility is false.
    * @private
    */
   showAdvancedSettings_: function(visibility) {
     return visibility !== false;
   },
 });