Oilpan: Make the Node hierarchy RefCountedGarbageCollected instead of TreeShared.

Source/core/dom/UserActionElementSet.h

Index: Source/core/dom/UserActionElementSet.h
diff --git a/Source/core/dom/UserActionElementSet.h b/Source/core/dom/UserActionElementSet.h
index 9883262c04fa6ed58faacf86d31e9a224ba2f11b..e150b972c92d1e011cfb5a1781e01030cee75e9e 100644
--- a/Source/core/dom/UserActionElementSet.h
+++ b/Source/core/dom/UserActionElementSet.h
@@ -27,6 +27,7 @@
 #ifndef UserActionElementSet_h
 #define UserActionElementSet_h
 
+#include "platform/heap/Handle.h"
 #include "wtf/HashMap.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/RefPtr.h"
@@ -37,9 +38,8 @@ class Node;
 class Element;
 
 class UserActionElementSet {
+    DISALLOW_ALLOCATION();
 public:
-    static PassOwnPtr<UserActionElementSet> create() { return adoptPtr(new UserActionElementSet()); }
-
     bool isFocused(const Node* node) { return hasFlags(node, IsFocusedFlag); }
     bool isActive(const Node* node) { return hasFlags(node, IsActiveFlag); }
     bool isInActiveChain(const Node* node) { return hasFlags(node, InActiveChainFlag); }
@@ -55,6 +55,8 @@ public:
     void didDetach(Node*);
     void documentDidRemoveLastRef();
 
+    void trace(Visitor*);
+
 private:
     enum ElementFlags {
         IsActiveFlag      = 1 ,
@@ -72,7 +74,7 @@ private:
     void clearFlags(Element*, unsigned);
     bool hasFlags(const Element*, unsigned flags) const;
 
-    typedef HashMap<RefPtr<Element>, unsigned> ElementFlagMap;
+    typedef WillBeHeapHashMap<RefPtrWillBeMember<Element>, unsigned> ElementFlagMap;
     ElementFlagMap m_elements;
 };