linux: fix race in TransportDIB passing

chrome/common/transport_dib.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 CHROME_COMMON_TRANSPORT_DIB_H_
 #define CHROME_COMMON_TRANSPORT_DIB_H_
 
 #include "base/basictypes.h"
 
 #if defined(OS_WIN) || defined(OS_MACOSX)
@@ skipping 124 matching lines @@
   explicit TransportDIB(base::SharedMemoryHandle dib);
   base::SharedMemory shared_memory_;
   uint32 sequence_num_;
 #elif defined(OS_LINUX)
   int key_;  // SysV shared memory id
   void* address_;  // mapped address
   XID x_shm_;  // X id for the shared segment
   Display* display_;  // connection to the X server
 #endif
   size_t size_;  // length, in bytes
+
+  DISALLOW_COPY_AND_ASSIGN(TransportDIB);
 };
 
 class MessageLoop;
 
 #endif  // CHROME_COMMON_TRANSPORT_DIB_H_