Remove scroll_clip_layer dependency from viewport layer tracking

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

 // 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.
 
 #ifndef TopDocumentRootScrollerController_h
 #define TopDocumentRootScrollerController_h
 
 #include "core/CoreExport.h"
 #include "core/page/scrolling/RootScrollerController.h"
 #include "platform/geometry/IntSize.h"
@@ skipping 39 matching lines @@
   // Returns true if the given ScrollStateCallback is the
   // ViewportScrollCallback managed by this class.
   // TODO(bokan): Temporarily needed to allow ScrollCustomization to
   // differentiate between real custom callback and the built-in viewport
   // apply scroll. crbug.com/623079.
   bool IsViewportScrollCallback(const ScrollStateCallback*) const;
 
   // Returns the GraphicsLayer for the global root scroller.
   GraphicsLayer* RootScrollerLayer() const;
 
+  // Returns the GraphicsLayer for the global root scroll container.
+  GraphicsLayer* RootContainerLayer() const;
+
   PaintLayer* RootScrollerPaintLayer() const;
 
   // Returns the Element that's the global root scroller.  See README.md for
   // the difference between this and the root scroller types in
   // RootScrollerController.
   Element* GlobalRootScroller() const;
 
   // Called when the root scroller in any frames on the page has changed.
   void DidChangeRootScroller();
 
@@ skipping 33 matching lines @@
   // m_viewportApplyScroll has been created, it will always be set on this
   // Element.
   WeakMember<Element> global_root_scroller_;
 
   Member<Page> page_;
 };
 
 }  // namespace blink
 
 #endif  // RootScrollerController_h