Remove unneeded enum forward declaration

ppapi/proxy/tcp_socket_resource.h

 // Copyright 2013 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 PPAPI_PROXY_TCP_SOCKET_RESOURCE_H_
 #define PPAPI_PROXY_TCP_SOCKET_RESOURCE_H_
 
 #include <stdint.h>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "ppapi/proxy/tcp_socket_resource_base.h"
 #include "ppapi/thunk/ppb_tcp_socket_api.h"
 
 namespace ppapi {
 
-enum TCPSocketVersion;
-
 namespace proxy {
 
 class PPAPI_PROXY_EXPORT TCPSocketResource : public thunk::PPB_TCPSocket_API,
                                              public TCPSocketResourceBase {
  public:
   // C-tor used for new sockets created.
   TCPSocketResource(Connection connection,
                     PP_Instance instance,
                     TCPSocketVersion version);
 
@@ skipping 42 matching lines @@
                     const PP_NetAddress_Private& local_addr,
                     const PP_NetAddress_Private& remote_addr);
 
   DISALLOW_COPY_AND_ASSIGN(TCPSocketResource);
 };
 
 }  // namespace proxy
 }  // namespace ppapi
 
 #endif  // PPAPI_PROXY_TCP_SOCKET_RESOURCE_H_