Revert r217952 to make behavior of horizontal scroll bar in page chrome://extensions keep consisten…

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="../uber/uber_utils.js"></include>
 <include src="extension_commands_overlay.js"></include>
 <include src="extension_focus_manager.js"></include>
 <include src="extension_list.js"></include>
 <include src="pack_extension_overlay.js"></include>
 
@@ skipping 338 matching lines @@
     return document.querySelector('#overlay .page.showing');
   }
 
   /**
    * Sets the given overlay to show. This hides whatever overlay is currently
    * showing, if any.
    * @param {HTMLElement} node The overlay page to show. If falsey, all overlays
    *     are hidden.
    */
   ExtensionSettings.showOverlay = function(node) {
+    var pageDiv = $('extension-settings');
+    if (node) {
+      pageDiv.style.width = window.getComputedStyle(pageDiv).width;
+      document.body.classList.add('no-scroll');
+    } else {
+      document.body.classList.remove('no-scroll');
+      pageDiv.style.width = '';
+    }
+
     var currentlyShowingOverlay = ExtensionSettings.getCurrentOverlay();
     if (currentlyShowingOverlay)
       currentlyShowingOverlay.classList.remove('showing');
 
     if (node)
       node.classList.add('showing');
 
     var pages = document.querySelectorAll('.page');
     for (var i = 0; i < pages.length; i++) {
       pages[i].setAttribute('aria-hidden', node ? 'true' : 'false');
@@ skipping 36 matching lines @@
 
   // Export
   return {
     ExtensionSettings: ExtensionSettings
   };
 });
 
 window.addEventListener('load', function(e) {
   extensions.ExtensionSettings.getInstance().initialize();
 });