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

chrome/browser/resources/settings/global_scroll_target_behavior.js

+// Copyright 2016 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 |GlobalScrollTargetBehavior| allows an element to be aware of
+ * the global scroll target. |scrollTarget| will be populated async by
+ * |setGlobalScrollTarget|. |setGlobalScrollTarget| should only be called once.
+ */
+
+cr.define('settings', function() {
+  var scrollTargetResolver = new PromiseResolver();
+
+  /** @polymerBehavior */
+  var GlobalScrollTargetBehavior = {
+    properties: {
+      /**
+       * Read only property for the scroll target.
+       * @type {HTMLElement}
+       */
+      scrollTarget: {
+        type: Object,
+        readOnly: true,
+      },
+    },
+
+    /** @override */
+    attached: function() {
+      scrollTargetResolver.promise.then(this._setScrollTarget.bind(this));
+    },
+  };
+
+  /**
+   * This should only be called once.
+   * @param {HTMLElement} scrollTarget
+   */
+  var setGlobalScrollTarget = function(scrollTarget) {
+    scrollTargetResolver.resolve(scrollTarget);
+  };
+
+  return {
+    GlobalScrollTargetBehavior: GlobalScrollTargetBehavior,
+    setGlobalScrollTarget: setGlobalScrollTarget,
+  };
+});