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

chrome/browser/resources/settings/bluetooth_page/bluetooth_device_dialog.html

 <link rel="import" href="chrome://resources/cr_elements/cr_dialog/cr_dialog.html">
 <link rel="import" href="chrome://resources/cr_elements/cr_scrollable_behavior.html">
 <link rel="import" href="chrome://resources/html/cr.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-flex-layout/classes/iron-flex-layout.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-list/iron-list.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-button/paper-button.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-input/paper-input.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-spinner/paper-spinner.html">
 <link rel="import" href="../bluetooth_page/bluetooth_device_list_item.html">
@@ skipping 66 matching lines @@
     <dialog is="cr-dialog" id="dialog" on-cancel="onDialogCanceled_"
         on-closed="onDialogCanceled_">
       <div class="title">$i18n{bluetoothPairDevicePageTitle}</div>
       <div class="body">
         <div class="contents layout vertical center center-justified">
           <!-- Note: dialog + dom-if + iron-list makes sizing complicated so use
                hidden here; this is almost always the first dialog shown. -->
           <div id="dialogDeviceList"
               hidden$="[[!isDialogType_(dialogId, 'addDevice')]]"
               class="layout vertical flex start self-stretch">
-            <span class="no-devices" hidden$="[[haveUnpaired_(deviceList.*)]]">
+            <span class="no-devices"
+                hidden$="[[haveUnpaired_(unpairedDeviceList_)]]">
               $i18n{bluetoothNoDevices}
             </span>
             <div id="container" class="layout vertical flex self-stretch"
                 scrollable>
-              <iron-list items="[[getUnpaired_(deviceList.*)]]"
-                  selection-enabled selected-item="{{selectedItem}}"
+              <iron-list id="devices" items="[[unpairedDeviceList_]]"
+                  selection-enabled selected-item="{{selectedItem_}}"
                   scroll-target="container">
                 <template>
                   <bluetooth-device-list-item device="[[item]]"
                       tabindex$="[[tabIndex]]">
                   </bluetooth-device-list-item>
                 </template>
               </iron-list>
             </div>
           </div>
           <template is="dom-if" if="[[isDialogType_(dialogId, 'pairDevice')]]">
@@ skipping 65 matching lines @@
         </template>
         <template is="dom-if" if="[[isDialogType_('connectError', dialogId)]]">
           <paper-button  on-tap="close">$i18n{bluetoothDismiss}
           </paper-button>
         </template>
       </div>
     </dialog>
   </template>
   <script src="bluetooth_device_dialog.js"></script>
 </dom-module>