Add 64bit support.

base/atomicops_internals_x86_msvc.h

Index: base/atomicops_internals_x86_msvc.h
===================================================================
--- base/atomicops_internals_x86_msvc.h	(revision 31316)
+++ base/atomicops_internals_x86_msvc.h	(working copy)
@@ -159,6 +159,19 @@
   return *ptr;
 }
 
+inline Atomic64 Acquire_CompareAndSwap(volatile Atomic64* ptr,
+                                       Atomic64 old_value,
+                                       Atomic64 new_value) {
+  return NoBarrier_CompareAndSwap(ptr, old_value, new_value);
+}
+
+inline Atomic64 Release_CompareAndSwap(volatile Atomic64* ptr,
+                                       Atomic64 old_value,
+                                       Atomic64 new_value) {
+  return NoBarrier_CompareAndSwap(ptr, old_value, new_value);
+}
+
+
 #endif  // defined(_WIN64)
 
 }  // namespace base::subtle