MD Settings: Preserve search URL param in subpages.

chrome/browser/resources/settings/settings_ui/settings_ui.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-ui' implements the UI for the Settings page.
  *
  * Example:
  *
@@ skipping 104 matching lines @@
 
   /** @override */
   attached: function() {
     // Preload bold Roboto so it doesn't load and flicker the first time used.
     document.fonts.load('bold 12px Roboto');
     settings.setGlobalScrollTarget(this.$.headerPanel.scroller);
   },
 
   /** @param {!settings.Route} route */
   currentRouteChanged: function(route) {
-    // New searches always take place on the BASIC route. Navigations into
-    // subpages are either non-searches, or continuations of an existing search.
-    //
-    // TODO(dpapad): Address corner-case where the user:
-    //  1) Visits a subpage first.
-    //  2) Triggers a search.
-    //  3) Clicks the "back" button.
-    //  Currently nothing happens. Should clear search results and navigate to
-    //  the subpage instead.
-    if (route.isSubpage())
-      return;
-
     var urlSearchQuery = settings.getQueryParameters().get('search') || '';
     if (urlSearchQuery == this.lastSearchQuery_)
       return;
 
     this.lastSearchQuery_ = urlSearchQuery;
 
     var toolbar = /** @type {!CrToolbarElement} */ (this.$$('cr-toolbar'));
     var searchField = /** @type {CrToolbarSearchFieldElement} */ (
         toolbar.getSearchField());
 
@@ skipping 17 matching lines @@
     // Trim leading whitespace only, to prevent searching for empty string. This
     // still allows the user to search for 'foo bar', while taking a long pause
     // after typing 'foo '.
     var query = e.detail.replace(/^\s+/, '');
     // Prevent duplicate history entries.
     if (query == this.lastSearchQuery_)
       return;
 
     settings.navigateTo(
         settings.Route.BASIC,
-        query.length > 0 ?
-            new URLSearchParams(`search=${query}`) : undefined);
+        query.length > 0 ? new URLSearchParams(`search=${query}`) : undefined,
+        /* removeSearch */ true);
   },
 
   /**
    * @param {Event} event
    * @private
    */
   onIronActivate_: function(event) {
     if (event.detail.item.id != 'advancedPage')
       this.$$('app-drawer').close();
   },
 
   /** @private */
   onMenuButtonTap_: function() {
     this.$$('app-drawer').toggle();
   },
 
   /** @private */
   directionDelegateChanged_: function() {
     this.$$('app-drawer').align = this.directionDelegate.isRtl() ?
         'right' : 'left';
   },
 });