Move ScrollbarManager from core to platform and use as Scrollbar parent

third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.h

 /*
  * Copyright (C) 2003, 2009, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 32 matching lines @@
 
 #ifndef PaintLayerScrollableArea_h
 #define PaintLayerScrollableArea_h
 
 #include <memory>
 #include "core/CoreExport.h"
 #include "core/layout/ScrollAnchor.h"
 #include "core/page/scrolling/StickyPositionScrollingConstraints.h"
 #include "core/paint/PaintInvalidationCapableScrollableArea.h"
 #include "core/paint/PaintLayerFragment.h"
-#include "core/paint/ScrollbarManager.h"
 #include "platform/heap/Handle.h"
+#include "platform/scroll/ScrollbarManager.h"
 #include "platform/wtf/PtrUtil.h"
 
 namespace blink {
 
 enum ResizerHitTestType { kResizerForPointer, kResizerForTouch };
 
 class ComputedStyle;
 class HitTestResult;
 class LayoutBox;
 class LayoutScrollbarPart;
@@ skipping 67 matching lines @@
     // causing pointless allocation/deallocation thrashing, and potentially
     // leading to other problems (crbug.com/528940).
 
     // ScrollbarManager allows a ScrollableArea to delay the destruction of a
     // scrollbar that is no longer needed, until the end of multi-pass layout.
     // If the scrollbar is then re-added before multi-pass layout finishes, the
     // previously "deleted" scrollbar will be restored, rather than constructing
     // a new one.
    public:
     ScrollbarManager(PaintLayerScrollableArea& scroller)
-        : blink::ScrollbarManager(scroller) {}
+        : blink::ScrollbarManager() {}
 
     void SetHasHorizontalScrollbar(bool has_scrollbar) override;
     void SetHasVerticalScrollbar(bool has_scrollbar) override;
 
     void DestroyDetachedScrollbars();
 
    protected:
     Scrollbar* CreateScrollbar(ScrollbarOrientation) override;
     void DestroyScrollbar(ScrollbarOrientation) override;
 
@@ skipping 448 matching lines @@
 
 DEFINE_TYPE_CASTS(PaintLayerScrollableArea,
                   ScrollableArea,
                   scrollableArea,
                   scrollableArea->IsPaintLayerScrollableArea(),
                   scrollableArea.IsPaintLayerScrollableArea());
 
 }  // namespace blink
 
 #endif  // LayerScrollableArea_h