MD Settings: Scroll to top when navigating to About page.

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

 // Copyright 2015 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.
 
 /** @fileoverview Suite of tests for the Settings basic page. */
 
 GEN_INCLUDE(['settings_page_browsertest.js']);
 
 /**
  * @constructor
@@ skipping 146 matching lines @@
           // Should (after some time) be scrolled to the On Startup section.
           var intervalId = window.setInterval(function() {
             if (page.scroller.scrollTop != 0) {
               window.clearInterval(intervalId);
               resolve();
             }
           }, 55);
         });
       });
     });
+
+    test('scroll to top before navigating to about', function() {
+      var page = self.getPage('basic');
+      // Set the viewport small to force the scrollbar to appear on ABOUT.
+      Polymer.dom().querySelector('settings-ui').style.height = '200px';
+
+      settings.navigateTo(settings.Route.ON_STARTUP);
+      assertNotEquals(0, page.scroller.scrollTop);
+
+      settings.navigateTo(settings.Route.ABOUT);

[dschuyler, 2017/01/17 23:33:38]

Could this need a Polymer.dom.flush() or something? It may be fine, I'm just
worried this may fail if a test bot hitches or something.

[tommycli, 2017/01/17 23:47:00]

Ah, I don't think it actually needs the flush. How about I add the flush() if
this fails CQ / we see test bots flaking on this?

+      assertEquals(0, page.scroller.scrollTop);
+    });
   });
 
   // Run all registered tests.
   mocha.run();
 });