Viewport apply scroll should be on the document element not scrollingElement.

third_party/WebKit/Source/core/dom/Document.h

Index: third_party/WebKit/Source/core/dom/Document.h
diff --git a/third_party/WebKit/Source/core/dom/Document.h b/third_party/WebKit/Source/core/dom/Document.h
index 0cb3924f19b25fb8a57849f2c0f2586ca97fbe09..6a7f6d6c640318b19de72989f029dc8fc47da8c1 100644
--- a/third_party/WebKit/Source/core/dom/Document.h
+++ b/third_party/WebKit/Source/core/dom/Document.h
@@ -1158,13 +1158,6 @@ private:
 
     const OriginAccessEntry& accessEntryFromURL();
 
-    // Installs the viewport scrolling callback (the "applyScroll" in Scroll
-    // Customization lingo) on the root scrollingElement. This callback is
-    // responsible for viewport related scroll actions like top controls
-    // movement and overscroll glow as well as actually scrolling the root
-    // viewport.
-    void updateViewportApplyScroll();
-
     DocumentLifecycle m_lifecycle;
 
     bool m_hasNodesWithPlaceholderStyle;
@@ -1271,10 +1264,6 @@ private:
 
     Member<Element> m_cssTarget;
 
-    // Not a WeakMember since we want to keep the scrollingElement around until
-    // we move its ApplyScroll onto the new scrollingElement.
-    Member<Element> m_oldScrollingElement;
-
     LoadEventProgress m_loadEventProgress;
 
     double m_startTime;