Move the Widget hierarchy to the Oilpan heap.

Source/core/frame/RemoteFrameView.h

Index: Source/core/frame/RemoteFrameView.h
diff --git a/Source/core/frame/RemoteFrameView.h b/Source/core/frame/RemoteFrameView.h
index ecce68ad11f96c4dce692c9b5cf37d8396051de6..ebe2231e2a4306aa6bc5ab99f01e2d00fa2dae47 100644
--- a/Source/core/frame/RemoteFrameView.h
+++ b/Source/core/frame/RemoteFrameView.h
@@ -13,9 +13,9 @@ namespace blink {
 
 class RemoteFrame;
 
-class RemoteFrameView : public Widget {
+class RemoteFrameView FINAL : public Widget {
 public:
-    static PassRefPtr<RemoteFrameView> create(RemoteFrame*);
+    static PassRefPtrWillBeRawPtr<RemoteFrameView> create(RemoteFrame*);
 
     virtual ~RemoteFrameView();
 
@@ -34,13 +34,15 @@ public:
 
     virtual void setFrameRect(const IntRect&) OVERRIDE;
 
+    virtual void trace(Visitor*) OVERRIDE;
+
 private:
     explicit RemoteFrameView(RemoteFrame*);
 
-    // The RefPtrWillBePersistent-cycle between RemoteFrame and its RemoteFrameView
-    // is broken in the same manner as FrameView::m_frame and LocalFrame::m_view is.
-    // See the FrameView::m_frame comment.
-    RefPtrWillBePersistent<RemoteFrame> m_remoteFrame;
+    // The RefPtr cycle between RemoteFrame and its RemoteFrameView is
+    // broken in the same manner as FrameView::m_frame and
+    // LocalFrame::m_view is. See the FrameView::m_frame comment.
+    RefPtrWillBeMember<RemoteFrame> m_remoteFrame;
 };
 
 DEFINE_TYPE_CASTS(RemoteFrameView, Widget, widget, widget->isRemoteFrameView(), widget.isRemoteFrameView());