MD Settings: Fix CrScrollableBehavior

ui/webui/resources/cr_elements/cr_scrollable_behavior.js

Index: ui/webui/resources/cr_elements/cr_scrollable_behavior.js
diff --git a/ui/webui/resources/cr_elements/cr_scrollable_behavior.js b/ui/webui/resources/cr_elements/cr_scrollable_behavior.js
index 59e1e53dab1b3e5885ebf1fc432df3a1ffc67b28..c5e52e7b2e621595a4da47ff2ddc285c417de0df 100644
--- a/ui/webui/resources/cr_elements/cr_scrollable_behavior.js
+++ b/ui/webui/resources/cr_elements/cr_scrollable_behavior.js
@@ -37,8 +37,11 @@
 /** @polymerBehavior */
 var CrScrollableBehavior = {
   properties: {
-    /** @private */
-    intervalId_: Number,
+    /** @private {number|null} */
+    intervalId_: {
+      type: Number,
+      value: null
+    }
   },
 
   ready: function() {
@@ -56,7 +59,7 @@ var CrScrollableBehavior = {
   },
 
   detached: function() {
-    if (this.intervalId_)
+    if (this.intervalId_ !== null)
       clearInterval(this.intervalId_);
   },
 
@@ -67,8 +70,10 @@ var CrScrollableBehavior = {
    */
   updateScrollableContents() {

[dpapad, 2016/11/23 18:30:21]

updateScrollableContents: function() {

[stevenjb, 2016/11/23 18:37:15]

Sigh. Still a C++ developer at heart. Done.

     let nodeList = this.root.querySelectorAll('[scrollable] iron-list');
-    // Use setTimeout to avoid initial render / sizing issues.
-    this.intervalId_ = setInterval(function() {
+    // Use setInterval to avoid initial render / sizing issues.
+    if (this.intervalId_ !== null)

[dpapad, 2016/11/23 18:30:21]

Can you move this before the querySelectorAll? So that we don't do any
unnecessary work if we are going to return early?

[stevenjb, 2016/11/23 18:37:15]

Good catch. Done.

+      return;
+    this.intervalId_ = window.setInterval(function() {
       let unreadyNodes = [];
       for (let node of nodeList) {
         if (node.parentNode.scrollHeight == 0) {
@@ -78,10 +83,12 @@ var CrScrollableBehavior = {
         let ironList = /** @type {!IronListElement} */ (node);
         ironList.notifyResize();
       }
-      if (unreadyNodes.length == 0)
-        clearInterval(this.intervalId_);
-      else
+      if (unreadyNodes.length == 0) {
+        window.clearInterval(this.intervalId_);
+        this.intervalId_ = null;
+      } else {
         nodeList = unreadyNodes;
+      }
     }.bind(this), 10);
   },