Remove Widget's dependency upon its own inheritor aka ScrollView. This was nasty from an OO design…

Source/core/platform/Widget.h

 /*
  * Copyright (C) 2004, 2005, 2006 Apple Computer, Inc.  All rights reserved.
  * Copyright (C) 2008 Collabora Ltd.  All rights reserved.
  * Copyright (C) 2013 Google 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.
@@ skipping 16 matching lines @@
 
 #ifndef Widget_h
 #define Widget_h
 
 #include "platform/geometry/IntRect.h"
 #include "wtf/Forward.h"
 #include "wtf/RefCounted.h"
 
 namespace WebCore {
 
-class AXObjectCache;
 class Cursor;
 class Event;
 class GraphicsContext;
-class ScrollView;
+class HostWindow;
 
 // The Widget class serves as a base class for three kinds of objects:
 // (1) Scrollable areas (ScrollView)
 // (2) Scrollbars (Scrollbar)
 // (3) Plugins (PluginView)
 //
-// Widgets are connected in a hierarchy, with the restriction that plugins and scrollbars are always leaves of the
-// tree.  Only ScrollViews can have children (and therefore the Widget class has no concept of children).
+// Widgets are connected in a hierarchy, with the restriction that plugins and
+// scrollbars are always leaves of the tree. Only ScrollViews can have children
+// (and therefore the Widget class has no concept of children).
 class Widget : public RefCounted<Widget> {
 public:
     Widget();
     virtual ~Widget();
 
     int x() const { return frameRect().x(); }
     int y() const { return frameRect().y(); }
     int width() const { return frameRect().width(); }
     int height() const { return frameRect().height(); }
     IntSize size() const { return frameRect().size(); }
@@ skipping 23 matching lines @@
     bool isVisible() const { return m_selfVisible && m_parentVisible; } // Whether or not we are actually visible.
     virtual void setParentVisible(bool visible) { m_parentVisible = visible; }
     void setSelfVisible(bool v) { m_selfVisible = v; }
 
     virtual bool isFrameView() const { return false; }
     virtual bool isPluginView() const { return false; }
     virtual bool isPluginContainer() const { return false; }
     virtual bool isScrollbar() const { return false; }
     virtual bool isScrollView() const { return false; }
 
-    void removeFromParent();
-    virtual void setParent(ScrollView* view);
-    ScrollView* parent() const { return m_parent; }
-    ScrollView* root() const;
+    virtual HostWindow* hostWindow() const;
+    virtual void setParent(Widget*);
+    Widget* parent() const { return m_parent; }
+    Widget* root() const;
 
     virtual void handleEvent(Event*) { }
 
     IntRect convertToRootView(const IntRect&) const;
     IntRect convertFromRootView(const IntRect&) const;
 
     IntPoint convertToRootView(const IntPoint&) const;
     IntPoint convertFromRootView(const IntPoint&) const;
 
     // It is important for cross-platform code to realize that Mac has flipped coordinates.  Therefore any code
@@ skipping 13 matching lines @@
 
     // Notifies this widget that its clip rect changed.
     virtual void clipRectChanged() { }
 
     // Virtual methods to convert points to/from the containing ScrollView
     virtual IntRect convertToContainingView(const IntRect&) const;
     virtual IntRect convertFromContainingView(const IntRect&) const;
     virtual IntPoint convertToContainingView(const IntPoint&) const;
     virtual IntPoint convertFromContainingView(const IntPoint&) const;
 
-    // A means to access the AX cache when this object can get a pointer to it.
-    virtual AXObjectCache* axObjectCache() const { return 0; }
+    // Virtual methods to convert points to/from child widgets
+    virtual IntPoint convertChildToSelf(const Widget*, const IntPoint&) const;
+    virtual IntPoint convertSelfToChild(const Widget*, const IntPoint&) const;
 
     // Notifies this widget that it will no longer be receiving events.
     virtual void eventListenersRemoved() { }
 
 private:
-    ScrollView* m_parent;
+    Widget* m_parent;
     IntRect m_frame;
     bool m_selfVisible;
     bool m_parentVisible;
 };
 
 } // namespace WebCore
 
 #endif // Widget_h