Revert of Remove indirection: setup scrollbar scroll layers in the scrollbar constructor

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

 /*
  * Copyright (C) 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 31 matching lines @@
 class CompositorAnimationHost;
 class CompositorAnimationTimeline;
 class LayoutBox;
 class LocalFrame;
 class FrameView;
 class GraphicsLayer;
 class Page;
 class PaintLayer;
 class Region;
 class ScrollableArea;
-class WebLayer;
 class WebLayerTreeView;
 class WebScrollbarLayer;
 
 class CORE_EXPORT ScrollingCoordinator final
     : public GarbageCollectedFinalized<ScrollingCoordinator> {
   WTF_MAKE_NONCOPYABLE(ScrollingCoordinator);
 
  public:
   static ScrollingCoordinator* create(Page*);
 
@@ skipping 36 matching lines @@
   // Should be called whenever the set of fixed objects changes.
   void frameViewFixedObjectsDidChange(FrameView*);
 
   // Should be called whenever the root layer for the given frame view changes.
   void frameViewRootLayerDidChange(FrameView*);
 
   std::unique_ptr<WebScrollbarLayer> createSolidColorScrollbarLayer(
       ScrollbarOrientation,
       int thumbThickness,
       int trackStart,
-      bool isLeftSideVerticalScrollbar,
-      WebLayer* scrollLayer);
+      bool isLeftSideVerticalScrollbar);
 
   void willDestroyScrollableArea(ScrollableArea*);
   // Returns true if the coordinator handled this change.
   bool scrollableAreaScrollLayerDidChange(ScrollableArea*);
   void scrollableAreaScrollbarLayerDidChange(ScrollableArea*,
                                              ScrollbarOrientation);
   void setLayerIsContainerForFixedPositionLayers(GraphicsLayer*, bool);
   void updateLayerPositionConstraint(PaintLayer*);
   void touchEventTargetRectsDidChange();
   void willDestroyLayer(PaintLayer*);
@@ skipping 64 matching lines @@
   ScrollbarMap m_verticalScrollbars;
   HashSet<const PaintLayer*> m_layersWithTouchRects;
   bool m_wasFrameScrollable;
 
   MainThreadScrollingReasons m_lastMainThreadScrollingReasons;
 };
 
 }  // namespace blink
 
 #endif  // ScrollingCoordinator_h