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diff --git a/ipc/chromium/src/base/thread_local_storage.h b/ipc/chromium/src/base/thread_local_storage.h
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+++ b/ipc/chromium/src/base/thread_local_storage.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+// 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_THREAD_LOCAL_STORAGE_H_
+#define BASE_THREAD_LOCAL_STORAGE_H_
+
+#include "base/basictypes.h"
+
+#if defined(OS_POSIX)
+#  include <pthread.h>
+#endif
+
+// Wrapper for thread local storage.  This class doesn't do much except provide
+// an API for portability.
+class ThreadLocalStorage {
+ public:
+  // Prototype for the TLS destructor function, which can be optionally used to
+  // cleanup thread local storage on thread exit.  'value' is the data that is
+  // stored in thread local storage.
+  typedef void (*TLSDestructorFunc)(void* value);
+
+  // A key representing one value stored in TLS.
+  class Slot {
+   public:
+    explicit Slot(TLSDestructorFunc destructor = NULL);
+
+    // This constructor should be used for statics.
+    // It returns an uninitialized Slot.
+    explicit Slot(base::LinkerInitialized x) {}
+
+    // Set up the TLS slot.  Called by the constructor.
+    // 'destructor' is a pointer to a function to perform per-thread cleanup of
+    // this object.  If set to NULL, no cleanup is done for this TLS slot.
+    // Returns false on error.
+    bool Initialize(TLSDestructorFunc destructor);
+
+    // Free a previously allocated TLS 'slot'.
+    // If a destructor was set for this slot, removes
+    // the destructor so that remaining threads exiting
+    // will not free data.
+    void Free();
+
+    // Get the thread-local value stored in slot 'slot'.
+    // Values are guaranteed to initially be zero.
+    void* Get() const;
+
+    // Set the thread-local value stored in slot 'slot' to
+    // value 'value'.
+    void Set(void* value);
+
+    bool initialized() const { return initialized_; }
+
+   private:
+    // The internals of this struct should be considered private.
+    bool initialized_;
+#if defined(OS_WIN)
+    int slot_;
+#elif defined(OS_POSIX)
+    pthread_key_t key_;
+#endif
+
+    DISALLOW_COPY_AND_ASSIGN(Slot);
+  };
+
+#if defined(OS_WIN)
+  // Function called when on thread exit to call TLS
+  // destructor functions.  This function is used internally.
+  static void ThreadExit();
+
+ private:
+  // Function to lazily initialize our thread local storage.
+  static void** Initialize();
+
+ private:
+  // The maximum number of 'slots' in our thread local storage stack.
+  // For now, this is fixed.  We could either increase statically, or
+  // we could make it dynamic in the future.
+  static const int kThreadLocalStorageSize = 64;
+
+  static long tls_key_;
+  static long tls_max_;
+  static TLSDestructorFunc tls_destructors_[kThreadLocalStorageSize];
+#endif  // OS_WIN
+
+  DISALLOW_COPY_AND_ASSIGN(ThreadLocalStorage);
+};
+
+// Temporary backwards-compatible name.
+// TODO(evanm): replace all usage of TLSSlot.
+typedef ThreadLocalStorage::Slot TLSSlot;
+
+#endif  // BASE_THREAD_LOCAL_STORAGE_H_