Unify and provide one IsGarbageCollectedType<T> implementation.

third_party/WebKit/Source/platform/heap/HeapAllocator.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 HeapAllocator_h
 #define HeapAllocator_h
 
 #include "platform/heap/Heap.h"
 #include "platform/heap/TraceTraits.h"
 #include "wtf/Allocator.h"
 #include "wtf/Assertions.h"
 #include "wtf/Deque.h"
 #include "wtf/HashCountedSet.h"
 #include "wtf/HashMap.h"
 #include "wtf/HashSet.h"
 #include "wtf/HashTable.h"
 #include "wtf/LinkedHashSet.h"
 #include "wtf/ListHashSet.h"
 #include "wtf/TypeTraits.h"
 #include "wtf/Vector.h"
 
 namespace blink {
 
 template<typename T, typename Traits = WTF::VectorTraits<T>> class HeapVectorBacking {
     DISALLOW_NEW();
+    IS_GARBAGE_COLLECTED_TYPE();
 public:
     static void finalize(void* pointer);
     void finalizeGarbageCollectedObject() { finalize(this); }
 };
 
 template<typename Table> class HeapHashTableBacking {
     DISALLOW_NEW();
+    IS_GARBAGE_COLLECTED_TYPE();
 public:
     static void finalize(void* pointer);
     void finalizeGarbageCollectedObject() { finalize(this); }
 };
 
 // This is a static-only class used as a trait on collections to make them heap
 // allocated.  However see also HeapListHashSetAllocator.
 class PLATFORM_EXPORT HeapAllocator {
     STATIC_ONLY(HeapAllocator);
 public:
@@ skipping 494 matching lines @@
 template<typename T, size_t inlineCapacity>
 struct NeedsTracing<ListHashSetNode<T, blink::HeapListHashSetAllocator<T, inlineCapacity>> *> {
     STATIC_ONLY(NeedsTracing);
     static_assert(sizeof(T), "T must be fully defined");
     // All heap allocated node pointers need visiting to keep the nodes alive,
     // regardless of whether they contain pointers to other heap allocated
     // objects.
     static const bool value = true;
 };
 
+template<typename T, size_t inlineCapacity>
+struct IsGarbageCollectedType<ListHashSetNode<T, blink::HeapListHashSetAllocator<T, inlineCapacity>>> {
+    static const bool value = true;
+};
+
 } // namespace WTF
 
 #endif