DeferredFreeListEntry
struct DeferredFreeListEntry : SinglyLinkedListLinkImpl<DeferredFreeListEntry> {
typedef SinglyLinkedList<DeferredFreeListEntry> DeferredFreeList;
while (DeferredFreeListEntry* entry = entries.RemoveHead())
DeferredFreeListEntry *entry = new(block) DeferredFreeListEntry;