blink: Cleanup core class forward declarations

third_party/WebKit/Source/core/layout/LayoutScrollbar.h

 /*
  * Copyright (C) 2008, 2009 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 17 matching lines @@
 
 #include "core/style/ComputedStyleConstants.h"
 #include "platform/heap/Handle.h"
 #include "platform/scroll/Scrollbar.h"
 #include "wtf/HashMap.h"
 
 namespace blink {
 
 class ComputedStyle;
 class LayoutBox;
-class LayoutBoxModelObject;
 class LayoutScrollbarPart;
 class LocalFrame;
 class Node;
-class PaintInvalidationState;
 
 class LayoutScrollbar final : public Scrollbar {
  public:
   static Scrollbar* createCustomScrollbar(ScrollableArea*,
                                           ScrollbarOrientation,
                                           Node*,
                                           LocalFrame* owningFrame = nullptr);
   ~LayoutScrollbar() override;
 
   LayoutBox* owningLayoutObject() const;
@@ skipping 54 matching lines @@
 
 DEFINE_TYPE_CASTS(LayoutScrollbar,
                   ScrollbarThemeClient,
                   scrollbar,
                   scrollbar->isCustomScrollbar(),
                   scrollbar.isCustomScrollbar());
 
 }  // namespace blink
 
 #endif  // LayoutScrollbar_h