Make lists in the passwords section aware of the scroll target.

chrome/browser/resources/settings/settings_ui/settings_ui.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
  * 'settings-ui' implements the UI for the Settings page.
  *
  * Example:
  *
@@ skipping 25 matching lines @@
     toolbarSpinnerActive_: {
       type: Boolean,
       value: false,
     },
 
     /**
      * Dictionary defining page visibility.
      * @private {!GuestModePageVisibility}
      */
     pageVisibility_: Object,
+
+    /**
+     * The scroll target for the lists in this section.
+     * @type {Element}
+     * @private
+     */
+    scrollTarget_: {
+      type: HTMLElement,
+      value: function() {
+        return this.$.headerPanel.scroller;
+      }
+    }
   },
 
   /** @override */
   created: function() {
     settings.initializeRouteFromUrl();
   },
 
   /**
    * @override
    * @suppress {es5Strict} Object literals cannot contain duplicate keys in ES5
@@ skipping 65 matching lines @@
   onMenuButtonTap_: function() {
     this.$$('app-drawer').toggle();
   },
 
   /** @private */
   directionDelegateChanged_: function() {
     this.$$('app-drawer').align = this.directionDelegate.isRtl() ?
         'right' : 'left';
   },
 });