Move thread_pool.h into utils so it can be shared by more than one example.

native_client_sdk/src/libraries/sdk_util/auto_lock.h

+/* Copyright (c) 2012 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 LIBRARIES_SDK_UTIL_AUTO_LOCK_H_
+#define LIBRARIES_SDK_UTIL_AUTO_LOCK_H_
+
+#include <pthread.h>
+
+class AutoLock {
+ public:
+  explicit AutoLock(pthread_mutex_t* lock) {
+    lock_ = lock;
+    pthread_mutex_lock(lock_);
+  }
+  ~AutoLock() {
+    if (lock_) pthread_mutex_unlock(lock_);
+  }
+
+  void Unlock() {
+    if (lock_) pthread_mutex_unlock(lock_);
+    lock_ = NULL;
+  }
+
+ private:
+  pthread_mutex_t* lock_;
+};
+
+#endif  // LIBRARIES_SDK_UTIL_AUTO_LOCK_H_
+