Make ViewportScrollCallback an interface and add child and root classes

third_party/WebKit/Source/core/page/scrolling/RootScrollerController.h

Index: third_party/WebKit/Source/core/page/scrolling/RootScrollerController.h
diff --git a/third_party/WebKit/Source/core/page/scrolling/RootScrollerController.h b/third_party/WebKit/Source/core/page/scrolling/RootScrollerController.h
index b42428a55f420b53fde6b5d51ce6e44532789db4..3535320b29ca8e5082cf0691367f0cfd9d28d00b 100644
--- a/third_party/WebKit/Source/core/page/scrolling/RootScrollerController.h
+++ b/third_party/WebKit/Source/core/page/scrolling/RootScrollerController.h
@@ -13,6 +13,7 @@ namespace blink {
 class Document;
 class Element;
 class OverscrollController;
+class RootViewportScrollCallback;

[tdresser, 2016/07/06 18:28:18]

Is this used?

[bokan, 2016/07/06 21:12:04]

Nope, removed. As well as OverscrollController and TopControls.

 class TopControls;
 class ViewportScrollCallback;
 
@@ -49,13 +50,6 @@ public:
         return new RootScrollerController(document, applyScrollCallback);
     }
 
-    // Creates an apply scroll callback that handles viewport actions like
-    // TopControls movement and Overscroll. The TopControls and
-    // OverscrollController are given to the ViewportScrollCallback but are not
-    // owned or kept alive by it.
-    static ViewportScrollCallback* createViewportApplyScroll(
-        TopControls*, OverscrollController*);
-
     DECLARE_TRACE();
 
     // Sets the element that will be used as the root scroller. This can be