MD Settings: make chrome://[md-]settings/clearBrowserData URL work

chrome/browser/resources/settings/settings_page/main_page_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.
 
 // Fast out, slow in.
 var EASING_FUNCTION = 'cubic-bezier(0.4, 0, 0.2, 1)';
 var EXPAND_DURATION = 350;
 
 /**
  * Workaround for scrolling an element into view when using Polymer.

[michaelpg, 2016/06/28 13:58:08]

fix comment

[Dan Beam, 2016/06/28 19:16:40]

Done.

- * @param {function():Element} containerCallback Return parent of element.
- * @param {function():Element} elementCallback Return element to scroll to.
+ * @param {function():boolean} readyTest
+ * @param {!Function} readyCallback
  */
-function scrollWhenReady(containerCallback, elementCallback) {
-  // TODO(dschuyler): Determine whether this setTimeout can be removed.
+function doWhenReady(readyTest, readyCallback) {

[michaelpg, 2016/06/28 13:58:08]

doWhenTrue?

[Dan Beam, 2016/06/28 19:16:40]

I don't think it's really unclear

[Dan Beam, 2016/06/28 19:18:28]

and if you change it to "doWhenTrue", it might be less clear that callback is
only called once (i.e. fire-once).  maybe this method gets repeatedly called and
fires trueCallback() every time trueTest() returns true?

+  // TODO(dschuyler): Determine whether this hack can be removed.
   // See also: https://github.com/Polymer/polymer/issues/3629
-  setTimeout(function pollForScrollHeight() {
-    var container = containerCallback();
-    if (!container || container.scrollHeight == 0) {
-      setTimeout(pollForScrollHeight.bind(this), 10);
-      return;
+  var intervalId = setInterval(function() {
+    if (readyTest()) {
+      clearInterval(intervalId);
+      readyCallback();
     }
-
-    elementCallback().scrollIntoView();
-  }.bind(this));
+  }, 10);
 }
 
 /**
  * Provides animations to expand and collapse individual sections in a page.
  * Expanded sections take up the full height of the container. At most one
  * section should be expanded at any given time.
  * @polymerBehavior Polymer.MainPageBehavior
  */
 var MainPageBehaviorImpl = {
   /**
@@ skipping 326 matching lines @@
     /** Contains the current route. */
     currentRoute: {
       type: Object,
       notify: true,
       observer: 'currentRouteChanged_',
     },
   },
 
   /** @private */
   scrollToSection_: function() {
-    scrollWhenReady(
+    doWhenReady(
         function() {
-          return this;
+          return this.scrollHeight > 0;
         }.bind(this),
         function() {
           // If the current section changes while we are waiting for the page to
           // be ready, scroll to the newest requested section.
-          return this.getSection_(this.currentRoute.section);
+          this.getSection_(this.currentRoute.section).scrollIntoView();
         }.bind(this));
   },
 
   /** @private */
   currentRouteChanged_: function(newRoute, oldRoute) {
     var newRouteIsSubpage = newRoute && newRoute.subpage.length;
     var oldRouteIsSubpage = oldRoute && oldRoute.subpage.length;
 
     if (!oldRoute && newRouteIsSubpage) {
       // Allow the page to load before expanding the section. TODO(michaelpg):
@@ skipping 32 matching lines @@
         this.$$('[section=' + section + ']'));
   },
 };
 
 
 /** @polymerBehavior */
 var RoutableBehavior = [
   MainPageBehavior,
   RoutableBehaviorImpl
 ];