MD Settings: Ensure that after clearing search, the "basic" page is displayed.

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.
 
 /**
  * @typedef {{about: boolean, basic: boolean, advanced: boolean}}
  */
 var MainPageVisibility;
 
 /**
@@ skipping 38 matching lines @@
      * @private {!MainPageVisibility}
      */
     showPages_: {
       type: Object,
       value: function() {
         return {about: false, basic: false, advanced: false};
       },
     },
 
     /**
-     * The main pages that were displayed before search was initiated. When
-     * |null| it indicates that currently the page is displaying its normal
-     * contents, instead of displaying search results.
-     * @private {?MainPageVisibility}
+     * Whether a search operation is in progress or previous search results are
+     * being displayed.
+     * @private {boolean}
      */
-    previousShowPages_: {
-      type: Object,
-      value: null,
+    inSearchMode_: {
+      type: Boolean,
+      value: false,
     },
 
     /** @private */
     showNoResultsFound_: {
       type: Boolean,
       value: false,
     },
 
     toolbarSpinnerActive: {
       type: Boolean,
@@ skipping 58 matching lines @@
    */
   arrowState_: function(opened) {
     return opened ? 'settings:arrow-drop-up' : 'cr:arrow-drop-down';
   },
 
   /**
    * @return {boolean}
    * @private
    */
   showAdvancedToggle_: function() {
-    var inSearchMode = !!this.previousShowPages_;
-    return !inSearchMode && this.showPages_.basic && !this.hasExpandedSection_;
+    return !this.inSearchMode_ && this.showPages_.basic &&
+        !this.hasExpandedSection_;
   },
 
   currentRouteChanged: function(newRoute) {
     // When the route changes from a sub-page to the main page, immediately
     // update hasExpandedSection_ to unhide the other sections.
     if (!newRoute.isSubpage())
       this.hasExpandedSection_ = false;
 
     if (settings.Route.ADVANCED.contains(newRoute))
       this.advancedToggleExpanded_ = true;
@@ skipping 97 matching lines @@
   ensureInDefaultSearchPage_: function() {
     if (settings.getCurrentRoute() != settings.Route.BASIC)
       settings.navigateTo(settings.Route.BASIC);
   },
 
   /**
    * @param {string} query
    * @return {!Promise} A promise indicating that searching finished.
    */
   searchContents: function(query) {
-    if (!this.previousShowPages_) {
-      // Store which pages are shown before search, so that they can be restored
-      // after the user clears the search results.
-      this.previousShowPages_ = this.showPages_;
-    }
-
+    this.inSearchMode_ = true;
     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};
 
     return new Promise(function(resolve, reject) {
       setTimeout(function() {
         var whenSearchDone = settings.getSearchManager().search(
             query, assert(this.getPage_(settings.Route.BASIC)));
         assert(
             whenSearchDone ===
                 settings.getSearchManager().search(
                     query, assert(this.getPage_(settings.Route.ADVANCED))));
 
         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;
-          var showingSearchResults = !request.isSame('');
+          this.inSearchMode_ = !request.isSame('');
           this.showNoResultsFound_ =
-              showingSearchResults && !request.didFindMatches();
+              this.inSearchMode_ && !request.didFindMatches();
 
-          if (!showingSearchResults) {
-            // Restore the pages that were shown before search was initiated.
-            this.showPages_ = assert(this.previousShowPages_);
-            this.previousShowPages_ = null;
+          if (!this.inSearchMode_) {
+            // Restore the "advanced" page visibility as it was before search
+            // was initiated.
+            this.showPages_ = {
+              about: false, basic: true, advanced: this.advancedToggleExpanded_,
+            };
           }
         }.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;
   },
 });