Test was examining a variable without first acquiring a required Lock....

base/lock.h

 // Copyright (c) 2006-2009 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_LOCK_H_
 #define BASE_LOCK_H_
 
 #include "base/lock_impl.h"
 
 // A convenient wrapper for an OS specific critical section.
 
 class Lock {
  public:
   Lock() : lock_() {}
   ~Lock() {}
   void Acquire() { lock_.Lock(); }
   void Release() { lock_.Unlock(); }
   // If the lock is not held, take it and return true. If the lock is already
   // held by another thread, immediately return false.
   bool Try() { return lock_.Try(); }
 
   // In debug builds this method checks that the lock has been acquired by the
   // calling thread.  If the lock has not been acquired, then the method
   // will DCHECK().  In non-debug builds, the LockImpl's implementation of
   // AssertAcquired() is an empty inline method.
-  void AssertAcquired() { return lock_.AssertAcquired(); }
+  void AssertAcquired() const { return lock_.AssertAcquired(); }
 
   // Return the underlying lock implementation.
   // TODO(awalker): refactor lock and condition variables so that this is
   // unnecessary.
   LockImpl* lock_impl() { return &lock_; }
 
  private:
   LockImpl lock_;  // Platform specific underlying lock implementation.
 
   DISALLOW_COPY_AND_ASSIGN(Lock);
@@ skipping 29 matching lines @@
   ~AutoUnlock() {
     lock_.Acquire();
   }
 
  private:
   Lock& lock_;
   DISALLOW_COPY_AND_ASSIGN(AutoUnlock);
 };
 
 #endif  // BASE_LOCK_H_