[Extensions] Make chrome://extensions use developerPrivate for error calls

chrome/browser/resources/extensions/extensions.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.
 
 <include src="../../../../ui/webui/resources/js/cr/ui/focus_row.js">
 <include src="../../../../ui/webui/resources/js/cr/ui/focus_grid.js">
 <include src="../uber/uber_utils.js">
 <include src="extension_code.js">
 <include src="extension_commands_overlay.js">
 <include src="extension_error_overlay.js">
@@ skipping 334 matching lines @@
 
   /**
    * Returns the current overlay or null if one does not exist.
    * @return {Element} The overlay element.
    */
   ExtensionSettings.getCurrentOverlay = function() {
     return document.querySelector('#overlay .page.showing');
   };
 
   /**
-   * Sets the given overlay to show. This hides whatever overlay is currently
-   * showing, if any.
+   * Sets the given overlay to show. If the overlay is already showing, this is
+   * a no-op; otherwise, hides any currently-showing overlay.
    * @param {HTMLElement} node The overlay page to show. If null, all overlays
    *     are hidden.
    */
   ExtensionSettings.showOverlay = function(node) {
     var pageDiv = $('extension-settings');
     pageDiv.style.width = node ? window.getComputedStyle(pageDiv).width : '';
     document.body.classList.toggle('no-scroll', !!node);
 
     var currentlyShowingOverlay = ExtensionSettings.getCurrentOverlay();
     if (currentlyShowingOverlay) {
+      if (currentlyShowingOverlay == node)  // Already displayed.
+        return;
       currentlyShowingOverlay.classList.remove('showing');
       cr.dispatchSimpleEvent($('overlay'), 'cancelOverlay');
     }
 
     if (node) {
       var lastFocused = document.activeElement;
       $('overlay').addEventListener('cancelOverlay', function f() {
         lastFocused.focus();
         $('overlay').removeEventListener('cancelOverlay', f);
       });
@@ skipping 62 matching lines @@
 
   // Export
   return {
     ExtensionSettings: ExtensionSettings
   };
 });
 
 window.addEventListener('load', function(e) {
   extensions.ExtensionSettings.getInstance().initialize();
 });