Move the Widget hierarchy to the Oilpan heap.

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 509b9dc0e099a29c5786010dcf2c1df239ece37d..63452ce0275534df330d8da26a9a2d8c27c452a9 100644
--- a/Source/core/frame/FrameView.h
+++ b/Source/core/frame/FrameView.h
@@ -63,8 +63,8 @@ public:
     friend class RenderView;
     friend class Internals;
 
-    static PassRefPtr<FrameView> create(LocalFrame*);
-    static PassRefPtr<FrameView> create(LocalFrame*, const IntSize& initialSize);
+    static PassRefPtrWillBeRawPtr<FrameView> create(LocalFrame*);
+    static PassRefPtrWillBeRawPtr<FrameView> create(LocalFrame*, const IntSize& initialSize);
 
     virtual ~FrameView();
 
@@ -85,7 +85,7 @@ public:
 
     virtual void setCanHaveScrollbars(bool) OVERRIDE;
 
-    virtual PassRefPtr<Scrollbar> createScrollbar(ScrollbarOrientation) OVERRIDE;
+    virtual PassRefPtrWillBeRawPtr<Scrollbar> createScrollbar(ScrollbarOrientation) OVERRIDE;
 
     virtual void setContentsSize(const IntSize&) OVERRIDE;
     IntPoint clampOffsetAtScale(const IntPoint& offset, float scale) const;
@@ -225,7 +225,7 @@ public:
     void incrementVisuallyNonEmptyPixelCount(const IntSize&);
     void setIsVisuallyNonEmpty() { m_isVisuallyNonEmpty = true; }
     void enableAutoSizeMode(const IntSize& minSize, const IntSize& maxSize);
-    void disableAutoSizeMode() { m_autoSizeInfo.clear(); }
+    void disableAutoSizeMode() { disposeAutoSizeInfo(); }
 
     void forceLayout(bool allowSubtree = false);
     void forceLayoutForPagination(const FloatSize& pageSize, const FloatSize& originalPageSize, float maximumShrinkFactor);
@@ -332,6 +332,9 @@ public:
     virtual GraphicsLayer* layerForVerticalScrollbar() const OVERRIDE;
     virtual GraphicsLayer* layerForScrollCorner() const OVERRIDE;
 
+    virtual void trace(Visitor*) OVERRIDE;
+    void dispose();
+
 protected:
     virtual bool scrollContentsFastPath(const IntSize& scrollDelta) OVERRIDE;
     virtual void scrollContentsSlowPath(const IntRect& updateRect) OVERRIDE;
@@ -417,6 +420,8 @@ private:
 
     void setLayoutSizeInternal(const IntSize&);
 
+    void disposeAutoSizeInfo();
+
     bool paintInvalidationIsAllowed() const
     {
         return !isInPerformLayout() || canInvalidatePaintDuringPerformLayout();
@@ -428,18 +433,16 @@ private:
     LayoutSize m_size;
 
     typedef WillBeHeapHashSet<RefPtrWillBeMember<RenderEmbeddedObject> > EmbeddedObjectSet;
-    WillBePersistentHeapHashSet<RefPtrWillBeMember<RenderEmbeddedObject> > m_widgetUpdateSet;
+    WillBeHeapHashSet<RefPtrWillBeMember<RenderEmbeddedObject> > m_widgetUpdateSet;
 
     // FIXME: These are just "children" of the FrameView and should be RefPtr<Widget> instead.
-    WillBePersistentHeapHashSet<RefPtrWillBeMember<RenderWidget> > m_widgets;
+    WillBeHeapHashSet<RefPtrWillBeMember<RenderWidget> > m_widgets;
 
-    // Oilpan: the use of a persistent back reference 'emulates' the
-    // RefPtr-cycle that is kept between the two objects non-Oilpan.
-    //
-    // That cycle is broken when a LocalFrame is detached by
-    // FrameLoader::detachFromParent(), it then clears its
-    // FrameView's m_frame reference by calling setView(nullptr).
-    RefPtrWillBePersistent<LocalFrame> m_frame;
+    // The RefPtr cycle between LocalFrame and FrameView is broken
+    // when a LocalFrame is detached by FrameLoader::detachFromParent(),
+    // it then clears its FrameView's m_frame reference by calling
+    // setView(nullptr).
+    RefPtrWillBeMember<LocalFrame> m_frame;
 
     bool m_doFullPaintInvalidation;
 
@@ -482,7 +485,7 @@ private:
     bool m_isTrackingPaintInvalidations; // Used for testing.
     Vector<IntRect> m_trackedPaintInvalidationRects;
 
-    RefPtrWillBePersistent<Node> m_nodeToDraw;
+    RefPtrWillBeMember<Node> m_nodeToDraw;
     PaintBehavior m_paintBehavior;
     bool m_isPainting;
 
@@ -491,15 +494,15 @@ private:
     bool m_isVisuallyNonEmpty;
     bool m_firstVisuallyNonEmptyLayoutCallbackPending;
 
-    RefPtrWillBePersistent<Node> m_maintainScrollPositionAnchor;
+    RefPtrWillBeMember<Node> m_maintainScrollPositionAnchor;
 
     // Renderer to hold our custom scroll corner.
-    RawPtrWillBePersistent<RenderScrollbarPart> m_scrollCorner;
+    RawPtrWillBeMember<RenderScrollbarPart> m_scrollCorner;
 
     OwnPtr<ScrollableAreaSet> m_scrollableAreas;
     OwnPtr<ResizerAreaSet> m_resizerAreas;
     OwnPtr<ViewportConstrainedObjectSet> m_viewportConstrainedObjects;
-    OwnPtr<FrameViewAutoSizeInfo> m_autoSizeInfo;
+    OwnPtrWillBeMember<FrameViewAutoSizeInfo> m_autoSizeInfo;
 
     float m_visibleContentScaleFactor;
     IntSize m_inputEventsOffsetForEmulation;
@@ -542,6 +545,7 @@ inline void FrameView::incrementVisuallyNonEmptyPixelCount(const IntSize& size)
 DEFINE_TYPE_CASTS(FrameView, Widget, widget, widget->isFrameView(), widget.isFrameView());
 
 class AllowPaintInvalidationScope {
+    STACK_ALLOCATED();
 public:
     explicit AllowPaintInvalidationScope(FrameView* view)
         : m_view(view)
@@ -560,8 +564,9 @@ public:
 
         m_view->setCanInvalidatePaintDuringPerformLayout(m_originalValue);
     }
+
 private:
-    FrameView* m_view;
+    RawPtrWillBeMember<FrameView> m_view;
     bool m_originalValue;
 };