1 files changed, 31 insertions, 0 deletions
diff --git a/base/atomic_sequence_num.h b/base/atomic_sequence_num.h
new file mode 100644
index 000000000000..11805a0ae501
--- /dev/null
+++ b/base/atomic_sequence_num.h
@@ -0,0 +1,31 @@
+// Copyright (c) 2006-2008 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 BASE_ATOMIC_SEQUENCE_NUM_H_
+#define BASE_ATOMIC_SEQUENCE_NUM_H_
+#pragma once
+
+#include "base/atomicops.h"
+#include "base/basictypes.h"
+
+namespace base {
+
+class AtomicSequenceNumber {
+ public:
+  AtomicSequenceNumber() : seq_(0) { }
+  explicit AtomicSequenceNumber(base::LinkerInitialized x) { /* seq_ is 0 */ }
+
+  int GetNext() {
+    return static_cast<int>(
+        base::subtle::NoBarrier_AtomicIncrement(&seq_, 1) - 1);
+  }
+
+ private:
+  base::subtle::Atomic32 seq_;
+  DISALLOW_COPY_AND_ASSIGN(AtomicSequenceNumber);
+};
+
+}  // namespace base
+
+#endif  // BASE_ATOMIC_SEQUENCE_NUM_H_