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

net/disk_cache/blockfile/trace.h

Index: net/disk_cache/blockfile/trace.h
diff --git a/net/disk_cache/blockfile/trace.h b/net/disk_cache/blockfile/trace.h
index 6805e6c60c27dedd06f69e8f4572afa3d5181669..48e370ca28d563c12e8980e90405fc19a75fe843 100644
--- a/net/disk_cache/blockfile/trace.h
+++ b/net/disk_cache/blockfile/trace.h
@@ -21,8 +21,10 @@ 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);