[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..a47172797218bcb470a2c00eccbc7c83ec2917a8 100644
--- a/chrome/test/data/webui/settings/basic_page_browsertest.js
+++ b/chrome/test/data/webui/settings/basic_page_browsertest.js
@@ -51,6 +51,24 @@ 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 = {
+        page: 'basic',
+        section: 'onStartup',
+        subpage: [],
+      };
+
+      return new Promise(function(resolve, reject) {
+        // This timeout should be longer than the one in main_page_behavior,

[Dan Beam, 2016/05/31 21:27:20]

can you just make scrollToSection_ return a Promise or dispatch an event for
testing or something?

[dschuyler, 2016/05/31 22:02:15]

In the 'or something' category I made the check independent
of the timeout value in scrollToSection_().

Done.

+        // scrollToSection_(). It may be removed if/when that timeout is
+        // removed.
+        setTimeout(resolve, 200);
+      });
+    });
   });
 
   // Run all registered tests.