base: add a thread-safety assertion checker

base/thread_local.h

 // Copyright (c) 2010 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.
 
 // WARNING: Thread local storage is a bit tricky to get right.  Please make
 // sure that this is really the proper solution for what you're trying to
 // achieve.  Don't prematurely optimize, most likely you can just use a Lock.
 //
-// These classes implement a warpper around the platform's TLS storage
+// These classes implement a wrapper around the platform's TLS storage
 // mechanism.  On construction, they will allocate a TLS slot, and free the
 // TLS slot on destruction.  No memory management (creation or destruction) is
 // handled.  This means for uses of ThreadLocalPointer, you must correctly
 // manage the memory yourself, these classes will not destroy the pointer for
 // you.  There are no at-thread-exit actions taken by these classes.
 //
 // ThreadLocalPointer<Type> wraps a Type*.  It performs no creation or
 // destruction, so memory management must be handled elsewhere.  The first call
 // to Get() on a thread will return NULL.  You can update the pointer with a
 // call to Set().
@@ skipping 93 matching lines @@
 
  private:
   ThreadLocalPointer<void> tlp_;
 
   DISALLOW_COPY_AND_ASSIGN(ThreadLocalBoolean);
 };
 
 }  // namespace base
 
 #endif  // BASE_THREAD_LOCAL_H_