Settings: Implement sub-subpages, and clean up some animations.

chrome/browser/resources/settings/search_page/search_page.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
  * 'cr-settings-search-page' is the settings page containing search settings.
  *
  * Example:
  *
@@ skipping 100 matching lines @@
 
     this.searchEngines = defaultEngines;
   },
 
   /** @private */
   manageSearchEngines_: function() {
     this.$.pages.navigateTo('search-engines');
   },
 
   /** @private */
+  searchEnginesSubpage_: function() {
+    this.$.pages.navigateTo('search-engines-subpage');
+  },
+
+  /** @private */
   handleBack_: function() {
     this.$.pages.back();
   },
 });