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

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

Index: chrome/browser/resources/settings/bluetooth_page/bluetooth_page.js
diff --git a/chrome/browser/resources/settings/bluetooth_page/bluetooth_page.js b/chrome/browser/resources/settings/bluetooth_page/bluetooth_page.js
index 66db1a9cf1c5244464a27de0d3f4e7fc0440d63c..ea9118f6f73ff5d147cb48db2428a82d2453dcc6 100644
--- a/chrome/browser/resources/settings/bluetooth_page/bluetooth_page.js
+++ b/chrome/browser/resources/settings/bluetooth_page/bluetooth_page.js
@@ -80,6 +80,17 @@ Polymer({
     },
 
     /**
+     * The ordered list of paired or connecting bluetooth devices.
+     * @type {!Array<!chrome.bluetooth.Device>}
+     */
+    pairedDeviceList_: {
+      type: Array,
+      value: /** @return {Array} */ function() {
+        return [];
+      },
+    },
+
+    /**
      * Reflects the iron-list selecteditem property.
      * @type {!chrome.bluetooth.Device}
      * @private
@@ -228,6 +239,14 @@ Polymer({
 
   /** @private */
   deviceListChanged_: function() {
+    var devices = this.$.devices;

[Dan Beam, 2017/02/01 06:13:17]

what's the point of this var?  |this| wont change here, afaict...

[stevenjb, 2017/02/02 01:17:47]

We use it twice below... Not sure I understand the question. I guess you're
saying that this.$.devices isn't long enough to merit the use of a local? Sounds
like a nit, but yeah, sure.

+    this.saveScroll(devices);
+    this.pairedDeviceList_ = this.deviceList_.filter(function(device) {
+      return !!device.paired || !!device.connecting;
+    });
+    this.updateScrollableContents();
+    this.restoreScroll(devices);
+
     for (var i = 0; i < this.deviceList_.length; ++i) {
       if (this.deviceList_[i].connected) {
         this.deviceConnected_ = true;
@@ -289,7 +308,6 @@ Polymer({
     }
     this.bluetooth.getDevices(function(devices) {
       this.deviceList_ = devices;
-      this.updateScrollableContents();
     }.bind(this));
   },
 
@@ -486,16 +504,6 @@ Polymer({
   },
 
   /**
-   * @return {!Array<!chrome.bluetooth.Device>}
-   * @private
-   */
-  getPairedOrConnecting_: function() {
-    return this.deviceList_.filter(function(device) {
-      return !!device.paired || !!device.connecting;
-    });
-  },
-
-  /**
    * @return {boolean} True if deviceList contains any paired devices.
    * @private
    */