base::RefCounted now DCHECKs when referenced from multiple threads.

net/disk_cache/blockfile/trace.h

 // Copyright (c) 2011 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.
 
 // This file provides support for basic in-memory tracing of short events. We
 // keep a static circular buffer where we store the last traced events, so we
 // can review the cache recent behavior should we need it.
 
 #ifndef NET_DISK_CACHE_BLOCKFILE_TRACE_H_
 #define NET_DISK_CACHE_BLOCKFILE_TRACE_H_
 
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 #include "net/base/net_export.h"
 
 namespace disk_cache {
 
 // Create and destroy the tracing buffer.
 void InitTrace(void);
 void DestroyTrace(void);
 
 // Simple class to handle the trace buffer lifetime. Any object interested in
 // tracing should keep a reference to the object returned by GetTraceObject().
-class TraceObject : public base::RefCounted<TraceObject> {
-  friend class base::RefCounted<TraceObject>;
+// TODO(mgiuca): Avoid using UnsafeRefCounted. http://crbug.com/469952.
+class TraceObject : public base::UnsafeRefCounted<TraceObject> {
+  friend class base::UnsafeRefCounted<TraceObject>;
+
  public:
   static TraceObject* GetTraceObject();
   void EnableTracing(bool enable);
 
  private:
   TraceObject();
   ~TraceObject();
   DISALLOW_COPY_AND_ASSIGN(TraceObject);
 };
 
 // Traces to the internal buffer.
 NET_EXPORT_PRIVATE void Trace(const char* format, ...);
 
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_BLOCKFILE_TRACE_H_