MD Settings: Save and restore scroll position in iron-list

chrome/browser/resources/settings/bluetooth_page/bluetooth_subpage.js

 // Copyright 2017 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-bluetooth-subpage' is the settings subpage for managing bluetooth
  *  properties and devices.
  */
 
@@ skipping 155 matching lines @@
     return this.bluetoothEnabled && !this.dialogId_;
   },
 
   /** @private */
   adapterStateChanged_: function() {
     this.updateDeviceList_();
   },
 
   /** @private */
   deviceListChanged_: function() {
-    var devices = this.$.devices;
+    this.saveScroll(this.$.devices);
     this.pairedDeviceList_ = this.deviceList_.filter(function(device) {
       return !!device.paired || !!device.connecting;
     });
     this.updateScrollableContents();
+    this.restoreScroll(this.$.devices);
   },
 
   /** @private */
   selectedItemChanged_: function() {
     if (this.selectedItem_)
       this.connectDevice_(this.selectedItem_);
   },
 
   /**
    * If bluetooth is enabled, request the complete list of devices and update
@@ skipping 215 matching lines @@
     this.startDiscovery_();
   },
 
   /** @private */
   onDialogClosed_: function() {
     this.stopDiscovery_();
     this.dialogId_ = '';
     this.pairingDevice_ = undefined;
   },
 });