MD Settings: Preserve search URL param in subpages.

chrome/browser/resources/settings/route.js

 // Copyright 2016 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.
 
 cr.define('settings', function() {
   /**
    * Class for navigable routes. May only be instantiated within this file.
    * @constructor
    * @param {string} path
    * @private
@@ skipping 302 matching lines @@
   var lastRouteChangeWasPopstate = function() {
     return lastRouteChangeWasPopstate_;
   };
 
   /**
    * Navigates to a canonical route and pushes a new history entry.
    * @param {!settings.Route} route
    * @param {URLSearchParams=} opt_dynamicParameters Navigations to the same
    *     search parameters in a different order will still push to history.
    */
-  var navigateTo = function(route, opt_dynamicParameters) {
+  var navigateTo = function(route, opt_dynamicParameters, opt_preserveSearch) {
+    var currentParams = getQueryParameters();
+    var oldSearchParam = currentParams.get('search') || '';
+
     var params = opt_dynamicParameters || new URLSearchParams();
+    var newSearchParam = params.get('search') || '';
 
     var url = route.path;
     if (opt_dynamicParameters) {
       var queryString = opt_dynamicParameters.toString();
       if (queryString)
         url += '?' + queryString;
     }
 
+    var preserveSearch = opt_preserveSearch == undefined ?
+        true : !!opt_preserveSearch;
+    if (preserveSearch && oldSearchParam.length > 0 &&
+        newSearchParam.length == 0) {
+      url += '?' + `search=${oldSearchParam}`;
+      params.append('search', oldSearchParam);
+    }
+

[tommycli, 2016/11/03 23:31:33]

I would recommend doing something like this on line 329:

if (preserveSearch && oldSearchParam && !newSearchParam)
  params.append('search', oldSearchParam)

I think then the URL will be taken care of by 334 automatically, and you don't
need this block.

[dpapad, 2016/11/04 02:00:33]

Done. I also removed the "if (opt_dynamicParameters) {" check completely. 

     // History serializes the state, so we don't push the actual route object.
     window.history.pushState(currentRoute_.path, '', url);
     setCurrentRoute(route, params, false);
   };
 
   /**
    * Navigates to the previous route if it has an equal or lesser depth.
    * If there is no previous route in history meeting those requirements,
    * this navigates to the immediate parent. This will never exit Settings.
    */
@@ skipping 19 matching lines @@
     RouteObserverBehavior: RouteObserverBehavior,
     getRouteForPath: getRouteForPath,
     initializeRouteFromUrl: initializeRouteFromUrl,
     getCurrentRoute: getCurrentRoute,
     getQueryParameters: getQueryParameters,
     lastRouteChangeWasPopstate: lastRouteChangeWasPopstate,
     navigateTo: navigateTo,
     navigateToPreviousRoute: navigateToPreviousRoute,
   };
 });