Introduce infrastructure for tracing ScriptWrappables.

third_party/WebKit/Source/bindings/core/v8/DOMWrapperMap.h

 /*
  * Copyright (C) 2012 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 75 matching lines @@
     {
         m_map.Clear();
     }
 
     void removeAndDispose(KeyType* key)
     {
         ASSERT(containsKey(key));
         m_map.Remove(key);
     }
 
+    void markWrapper(KeyType* object)
+    {
+        m_map.RegisterExternallyReferencedObject(object);
+    }
+
 private:
     class PersistentValueMapTraits {
         STATIC_ONLY(PersistentValueMapTraits);
     public:
         // Map traits:
         typedef HashMap<KeyType*, v8::PersistentContainerValue> Impl;
         typedef typename Impl::iterator Iterator;
         static size_t Size(const Impl* impl) { return impl->size(); }
         static bool Empty(Impl* impl) { return impl->isEmpty(); }
         static void Swap(Impl& impl, Impl& other) { impl.swap(other); }
@@ skipping 50 matching lines @@
         static void DisposeWeak(const v8::WeakCallbackInfo<WeakCallbackDataType>&);
     };
 
     v8::Isolate* m_isolate;
     typename PersistentValueMapTraits::MapType m_map;
 };
 
 } // namespace blink
 
 #endif // DOMWrapperMap_h