Make sure read/write buffer alive in TCPSocketLibevent.

net/socket/tcp_socket_libevent.h

Index: net/socket/tcp_socket_libevent.h
diff --git a/net/socket/tcp_socket_libevent.h b/net/socket/tcp_socket_libevent.h
index 59978aa3bb3969b256bc73cd41166566121e3da9..0335c9ea2dea0587ad6ff29421f3a2b3176363dd 100644
--- a/net/socket/tcp_socket_libevent.h
+++ b/net/socket/tcp_socket_libevent.h
@@ -148,12 +148,12 @@ class NET_EXPORT TCPSocketLibevent {
   void LogConnectBegin(const AddressList& addresses) const;
   void LogConnectEnd(int net_error) const;
 
-  void ReadCompleted(IOBuffer* buf,
+  void ReadCompleted(const scoped_refptr<IOBuffer>& buf,
                      const CompletionCallback& callback,
                      int rv);
   int HandleReadCompleted(IOBuffer* buf, int rv);
 
-  void WriteCompleted(IOBuffer* buf,
+  void WriteCompleted(const scoped_refptr<IOBuffer>& buf,
                       const CompletionCallback& callback,
                       int rv) const;
   int HandleWriteCompleted(IOBuffer* buf, int rv) const;