Fix race at blink::GCInfoAtBase<T>::index

Source/platform/heap/GCInfo.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef GCInfo_h
 #define GCInfo_h
 
 #include "platform/heap/Visitor.h"
 #include "wtf/Assertions.h"
 #include "wtf/Atomics.h"
@@ skipping 93 matching lines @@
 
 // GCInfo contains meta-data associated with objects allocated in the
 // Blink heap. This meta-data consists of a function pointer used to
 // trace the pointers in the object during garbage collection, an
 // indication of whether or not the object needs a finalization
 // callback, and a function pointer used to finalize the object when
 // the garbage collector determines that the object is no longer
 // reachable. There is a GCInfo struct for each class that directly
 // inherits from GarbageCollected or GarbageCollectedFinalized.
 struct GCInfo {
+    using GetClassNameCallback = const String& (*)();
+
     bool hasFinalizer() const { return m_nonTrivialFinalizer; }
     bool hasVTable() const { return m_hasVTable; }
-    const String& className() const { return m_className; }
+    const String& className() const { return m_classNameGetter(); }
     TraceCallback m_trace;
     FinalizationCallback m_finalize;
     bool m_nonTrivialFinalizer;
     bool m_hasVTable;
-    // |m_className| is held as a reference to prevent dtor being called at exit.
-    const String& m_className;
+    GetClassNameCallback m_classNameGetter;
 };
 
 #if ENABLE(ASSERT)
 PLATFORM_EXPORT void assertObjectHasGCInfo(const void*, size_t gcInfoIndex);
 #endif
 
 class GCInfoTable {
 public:
     PLATFORM_EXPORT static void ensureGCInfoIndex(const GCInfo*, size_t*);
 
@@ skipping 31 matching lines @@
 template<typename T>
 struct GCInfoAtBase {
     static size_t index()
     {
         static_assert(sizeof(T), "T must be fully defined");
         static const GCInfo gcInfo = {
             TraceTrait<T>::trace,
             FinalizerTrait<T>::finalize,
             FinalizerTrait<T>::nonTrivialFinalizer,
             WTF::IsPolymorphic<T>::value,
-            TypenameStringTrait<T>::get()
+            TypenameStringTrait<T>::get
         };
         RETURN_GCINFO_INDEX();
     }
 };
 
 template<typename T, bool = WTF::IsSubclassOfTemplate<typename WTF::RemoveConst<T>::Type, GarbageCollected>::value> struct GetGarbageCollectedBase;
 
 template<typename T>
 struct GetGarbageCollectedBase<T, true> {
     typedef typename T::GarbageCollectedBase type;
@@ skipping 33 matching lines @@
 template<typename T, size_t inlineCapacity>
 struct GCInfoTrait<HeapVector<T, inlineCapacity>> : public GCInfoTrait<Vector<T, inlineCapacity, HeapAllocator>> { };
 template<typename T, size_t inlineCapacity>
 struct GCInfoTrait<HeapDeque<T, inlineCapacity>> : public GCInfoTrait<Deque<T, inlineCapacity, HeapAllocator>> { };
 template<typename T, typename U, typename V>
 struct GCInfoTrait<HeapHashCountedSet<T, U, V>> : public GCInfoTrait<HashCountedSet<T, U, V, HeapAllocator>> { };
 
 } // namespace blink
 
 #endif