Don't pushState when setting the search page to itself.

chrome/browser/resources/options/search_page.js

 // Copyright (c) 2012 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('options', function() {
   /** @const */ var Page = cr.ui.pageManager.Page;
   /** @const */ var PageManager = cr.ui.pageManager.PageManager;
 
   /**
    * Encapsulated handling of a search bubble.
@@ skipping 249 matching lines @@
      * @private
      */
     setSearchText_: function(text) {
       // Prevent recursive execution of this method.
       if (this.insideSetSearchText_) return;
       this.insideSetSearchText_ = true;
 
       // Cleanup the search query string.
       text = SearchPage.canonicalizeQuery(text);
 
-      // Set the hash on the current page, and the enclosing uber page
+      // Set the hash on the current page, and the enclosing uber page. Only do
+      // this if the page is not current. See https://crbug.com/401004.
       var hash = text ? '#' + encodeURIComponent(text) : '';
       var path = text ? this.name : '';
-      uber.pushState({}, path + hash);
+      if (location.hash != hash || location.pathname != '/' + path)
+        uber.pushState({}, path + hash);
 
       // Toggle the search page if necessary.
       if (text) {
         if (!this.searchActive_)
           PageManager.showPageByName(this.name, false);
       } else {
         if (this.searchActive_)
           PageManager.showDefaultPage(false);
 
         this.insideSetSearchText_ = false;
@@ skipping 282 matching lines @@
     // Trim beginning and ending whitespace.
     return text.replace(/^\s+|\s+$/g, '');
   };
 
   // Export
   return {
     SearchPage: SearchPage
   };
 
 });