Revert of Switch wtf/SpinLock to std::atomic

third_party/WebKit/Source/wtf/Partitions.cpp

Index: third_party/WebKit/Source/wtf/Partitions.cpp
diff --git a/third_party/WebKit/Source/wtf/Partitions.cpp b/third_party/WebKit/Source/wtf/Partitions.cpp
index 2e97e011efebd74f183c15f915778ec8ca7b9a0e..39914b4a9c89e2712cf0ac58fb024839bfaaa612 100644
--- a/third_party/WebKit/Source/wtf/Partitions.cpp
+++ b/third_party/WebKit/Source/wtf/Partitions.cpp
@@ -39,7 +39,7 @@
 
 const char* const Partitions::kAllocatedObjectPoolName = "partition_alloc/allocated_objects";
 
-SpinLock Partitions::s_initializationLock;
+int Partitions::s_initializationLock = 0;
 bool Partitions::s_initialized = false;
 
 PartitionAllocatorGeneric Partitions::m_fastMallocAllocator;
@@ -50,7 +50,7 @@
 
 void Partitions::initialize(HistogramEnumerationFunction histogramEnumeration)
 {
-    SpinLock::Guard guard(s_initializationLock);
+    spinLockLock(&s_initializationLock);
 
     if (!s_initialized) {
         partitionAllocGlobalInit(&Partitions::handleOutOfMemory);
@@ -61,11 +61,13 @@
         m_histogramEnumeration = histogramEnumeration;
         s_initialized = true;
     }
+
+    spinLockUnlock(&s_initializationLock);
 }
 
 void Partitions::shutdown()
 {
-    SpinLock::Guard guard(s_initializationLock);
+    spinLockLock(&s_initializationLock);
 
     // We could ASSERT here for a memory leak within the partition, but it leads
     // to very hard to diagnose ASSERTs, so it's best to leave leak checking for
@@ -76,6 +78,8 @@
         (void) m_bufferAllocator.shutdown();
         (void) m_fastMallocAllocator.shutdown();
     }
+
+    spinLockUnlock(&s_initializationLock);
 }
 
 void Partitions::decommitFreeableMemory()