chrome://settings - Provide method for pages to prevent themselves being shown.

chrome/browser/resources/options/add_startup_page_overlay.js

 // Copyright (c) 2011 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 OptionsPage = options.OptionsPage;
   const ArrayDataModel = cr.ui.ArrayDataModel;
   const ListSingleSelectionModel = cr.ui.ListSingleSelectionModel;
 
   /**
@@ skipping 93 matching lines @@
 
     /**
       * Sets the value of the input field to the given string.
       * @private
       * @param {string} url String value to set the input field to.
       */
     setInputFieldValue_: function(url) {
       $('addStartupPageURL').value = url;
       this.updateAddButtonState_();
     },
+
+    /** @inheritDoc */
+    canShowPage: function() {
+      return BrowserOptions.getInstance().
+          shouldEnableCustomStartupPageControls();
+    },
   };
 
   AddStartupPageOverlay.updateRecentPageList = function(pages) {
     AddStartupPageOverlay.getInstance().updateRecentPageList_(pages);
   };
 
   AddStartupPageOverlay.setInputFieldValue = function(url) {
     AddStartupPageOverlay.getInstance().setInputFieldValue_(url);
   };
 
   // Export
   return {
     AddStartupPageOverlay: AddStartupPageOverlay
   };
 
 });