Switch wtf/SpinLock to std::atomic

third_party/WebKit/Source/wtf/Partitions.h

 /*
  * Copyright (C) 2013 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 107 matching lines @@
         return partitionReallocGeneric(Partitions::fastMallocPartition(), p, n, typeName);
     }
     static void fastFree(void* p)
     {
         partitionFreeGeneric(Partitions::fastMallocPartition(), p);
     }
 
     static void handleOutOfMemory();
 
 private:
-    static int s_initializationLock;
+    static SpinLock s_initializationLock;
     static bool s_initialized;
 
     // We have the following four partitions.
     //   - Node partition: A partition to allocate Nodes. We prepare a
     //     dedicated partition for Nodes because Nodes are likely to be
     //     a source of use-after-frees. Another reason is for performance:
     //     Since Nodes are guaranteed to be used only by the main
     //     thread, we can bypass acquiring a lock. Also we can improve memory
     //     locality by putting Nodes together.
     //   - Layout object partition: A partition to allocate LayoutObjects.
     //     we prepare a dedicated partition for the same reason as Nodes.
     //   - Buffer partition: A partition to allocate objects that have a strong
     //     risk where the length and/or the contents are exploited from user
     //     scripts. Vectors, HashTables, ArrayBufferContents and Strings are
     //     allocated in the buffer partition.
     //   - Fast malloc partition: A partition to allocate all other objects.
     static PartitionAllocatorGeneric m_fastMallocAllocator;
     static PartitionAllocatorGeneric m_bufferAllocator;
     static SizeSpecificPartitionAllocator<3328> m_nodeAllocator;
     static SizeSpecificPartitionAllocator<1024> m_layoutAllocator;
     static HistogramEnumerationFunction m_histogramEnumeration;
 };
 
 } // namespace WTF
 
 #endif // Partitions_h