Oilpan: Move LifecycleNotifier's hierarchy to Oilpan's heap

Source/platform/Supplementable.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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 134 matching lines @@
 
     static SupplementBase<T, isGarbageCollected>* from(SupplementableBase<T, isGarbageCollected>* host, const char* key)
     {
         return host ? host->requireSupplement(key) : 0;
     }
 };
 
 template<typename T, bool isGarbageCollected>
 class SupplementableTracing;
 
+// Using a virtual inheritance to resolve a diamond inheritance
+// in ExecutionContext.
 template<typename T>
-class SupplementableTracing<T, true> : public GarbageCollectedMixin {
+class SupplementableTracing<T, true> : public virtual GarbageCollectedMixin {
 public:
     virtual void trace(Visitor* visitor)
     {
         visitor->trace(m_supplements);
     }
 
 protected:
     typedef HeapHashMap<const char*, Member<SupplementBase<T, true>>, PtrHash<const char*>> SupplementMap;
     SupplementMap m_supplements;
 };
@@ skipping 62 matching lines @@
 };
 
 template<typename T>
 struct ThreadingTrait<SupplementableBase<T, true>> {
     static const ThreadAffinity Affinity = ThreadingTrait<T>::Affinity;
 };
 
 } // namespace blink
 
 #endif // Supplementable_h