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

base/lock_impl.h

 // 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_LOCK_IMPL_H_
 #define BASE_LOCK_IMPL_H_
 
 #include "build/build_config.h"
 
 #if defined(OS_WIN)
@@ skipping 29 matching lines @@
   // Release the lock.  This must only be called by the lock's holder: after
   // a successful call to Try, or a call to Lock.
   void Unlock();
 
   // Debug-only method that will DCHECK() if the lock is not acquired by the
   // current thread.  In non-debug builds, no check is performed.
   // Because linux and mac condition variables modify the underlyning lock
   // through the os_lock() method, runtime assertions can not be done on those
   // builds.
 #if defined(NDEBUG) || !defined(OS_WIN)
-  void AssertAcquired() {}
+  void AssertAcquired() const {}
 #else
-  void AssertAcquired();
+  void AssertAcquired() const;
 #endif
 
   // Return the native underlying lock.  Not supported for Windows builds.
   // TODO(awalker): refactor lock and condition variables so that this is
   // unnecessary.
 #if !defined(OS_WIN)
   OSLockType* os_lock() { return &os_lock_; }
 #endif
 
  private:
   OSLockType os_lock_;
 
 #if !defined(NDEBUG) && defined(OS_WIN)
   // All private data is implicitly protected by lock_.
   // Be VERY careful to only access members under that lock.
   PlatformThreadId owning_thread_id_;
   int32 recursion_count_shadow_;
   bool recursion_used_;      // Allow debugging to continued after a DCHECK().
 #endif  // NDEBUG
 
   DISALLOW_COPY_AND_ASSIGN(LockImpl);
 };
 
 
 #endif  // BASE_LOCK_IMPL_H_