Harden the machinery around updateWidgetPositions()

Source/core/frame/FrameView.h

Index: Source/core/frame/FrameView.h
diff --git a/Source/core/frame/FrameView.h b/Source/core/frame/FrameView.h
index 5cad0ffd0f641d3dd12179b6c3beb37bcd44635a..66c9cf1add90621f93cae9fea6046d00dabd1a2e 100644
--- a/Source/core/frame/FrameView.h
+++ b/Source/core/frame/FrameView.h
@@ -50,6 +50,7 @@ class RenderEmbeddedObject;
 class RenderObject;
 class RenderScrollbarPart;
 class RenderStyle;
+class RenderWidget;
 
 Pagination::Mode paginationModeForRenderStyle(RenderStyle*);
 
@@ -211,6 +212,10 @@ public:
     bool safeToPropagateScrollToParent() const { return m_safeToPropagateScrollToParent; }
     void setSafeToPropagateScrollToParent(bool isSafe) { m_safeToPropagateScrollToParent = isSafe; }
 
+    void addWidget(RenderWidget*);
+    void removeWidget(RenderWidget*);
+    void updateWidgetPositions();
+
     void addWidgetToUpdate(RenderEmbeddedObject&);
 
     virtual void paintContents(GraphicsContext*, const IntRect& damageRect) OVERRIDE;
@@ -458,6 +463,9 @@ private:
     typedef HashSet<RefPtr<RenderEmbeddedObject> > EmbeddedObjectSet;
     EmbeddedObjectSet m_widgetUpdateSet;
 
+    // FIXME: These are just "children" of the FrameView and should be RefPtr<Widget> instead.
+    HashSet<RefPtr<RenderWidget> > m_widgets;
+
     RefPtr<Frame> m_frame;
 
     bool m_doFullRepaint;