Add virtual destructors for the Pepper API thunks.

ppapi/thunk/ppb_flash_net_connector_api.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.
 
 #ifndef PPAPI_THUNK_PPB_FLASH_NET_CONNECTOR_API_H_
 #define PPAPI_THUNK_PPB_FLASH_NET_CONNECTOR_API_H_
 
 #include "ppapi/c/private/ppb_flash_net_connector.h"
 
 namespace ppapi {
 namespace thunk {
 
 class PPB_Flash_NetConnector_API {
  public:
+  virtual ~PPB_Flash_NetConnector_API() {}
+
   virtual int32_t ConnectTcp(const char* host,
                              uint16_t port,
                              PP_FileHandle* socket_out,
                              PP_Flash_NetAddress* local_addr_out,
                              PP_Flash_NetAddress* remote_addr_out,
                              PP_CompletionCallback callback) = 0;
   virtual int32_t ConnectTcpAddress(const PP_Flash_NetAddress* addr,
                                     PP_FileHandle* socket_out,
                                     PP_Flash_NetAddress* local_addr_out,
                                     PP_Flash_NetAddress* remote_addr_out,
                                     PP_CompletionCallback callback) = 0;
 };
 
 }  // namespace thunk
 }  // namespace ppapi
 
 #endif  // PPAPI_THUNK_PPB_FLASH_NET_CONNECTOR_API_H_