[MD settings] scroll to section find host

chrome/test/data/webui/settings/basic_page_browsertest.js

Index: chrome/test/data/webui/settings/basic_page_browsertest.js
diff --git a/chrome/test/data/webui/settings/basic_page_browsertest.js b/chrome/test/data/webui/settings/basic_page_browsertest.js
index 7410b9b02a81c053268c2f0de948c34134293d46..4a9c9fe458830e76d09f0314aa411e8b445a0e21 100644
--- a/chrome/test/data/webui/settings/basic_page_browsertest.js
+++ b/chrome/test/data/webui/settings/basic_page_browsertest.js
@@ -51,6 +51,27 @@ TEST_F('SettingsBasicPageBrowserTest', 'MAYBE_Load', function() {
         self.verifySubpagesHidden(section);
       }
     });
+
+    // This test checks for a regression that occurred with scrollToSection_
+    // failing to find its host element.
+    test('scroll to section', function() {
+      // Setting the page and section will cause a scrollToSection_.
+      self.getPage('basic').currentRoute = {

[michaelpg, 2016/06/06 20:13:03]

Since this is a test of the entire page, why not trigger the actual interaction
being tested (tapping an item in the settings-menu)?

+        page: 'basic',
+        section: 'onStartup',
+        subpage: [],
+      };
+
+      return new Promise(function(resolve, reject) {
+        var intervalId = window.setInterval(function() {
+          var page = self.getPage('basic');
+          if (self.getSection(page, page.currentRoute.section)) {

[michaelpg, 2016/06/06 20:13:04]

Why not actually *check* page.scroller.scrollTop to confirm the page has
scrolled?

+            window.clearInterval(intervalId);
+            resolve();
+          }
+        }, 55);

[michaelpg, 2016/06/06 20:13:03]

This is an unnecessary use of setInterval when setTimeout with a 0 timeout would
suffice.

+      }.bind(self));
+    });
   });
 
   // Run all registered tests.