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

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.
 
 /**
  * Responds to route changes by expanding, collapsing, or scrolling to sections
  * on the page. Expanded sections take up the full height of the container. At
  * most one section should be expanded at any given time.
  * @polymerBehavior MainPageBehavior
  */
@@ skipping 30 matching lines @@
     var oldRouteWasSection =
         !!oldRoute && !!oldRoute.parent && !!oldRoute.section &&
         oldRoute.parent.section != oldRoute.section;
 
     // Always scroll to the top if navigating from a section to the root route.
     if (oldRouteWasSection && newRoute == settings.Route.BASIC) {
       this.scroller.scrollTop = 0;
       return;
     }
 
+    // Always scroll to the top when navigating to the About page.

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

I'm not sure about this, but WDYT about combining with the condition above?

// Always scroll to the top if navigating from a section to the root route
// or when navigating to the About page.
if ((oldRouteWasSection && newRoute == settings.Route.BASIC) ||
    (newRoute == settings.Route.ABOUT && this.scroller)) {
  ...
}

My concern is that if something about the body of the code needs to change in
the future, the person making that change may miss that both blocks do the same
thing and only change one of them.
If you feel that it's better as two separate condition blocks, please let me
know. 

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

Done.

+    if (newRoute == settings.Route.ABOUT && this.scroller) {
+      this.scroller.scrollTop = 0;
+      return;
+    }
+
     // Scroll to the section except for back/forward. Also scroll for any
     // in-page back/forward navigations (from a section or the root page).
     var scrollToSection =
         !settings.lastRouteChangeWasPopstate() || oldRouteWasSection ||
         oldRoute == settings.Route.BASIC;
 
     // For previously uncreated pages (including on first load), allow the page
     // to render before scrolling to or expanding the section.
     if (!oldRoute || this.scrollHeight == 0)
       setTimeout(this.tryTransitionToSection_.bind(this, scrollToSection));
@@ skipping 240 matching lines @@
     return /** @type {?SettingsSectionElement} */(
         this.$$('settings-section[section="' + section + '"]'));
   },
 };
 
 /** @polymerBehavior */
 var MainPageBehavior = [
   settings.RouteObserverBehavior,
   MainPageBehaviorImpl,
 ];