PPAPI: Make blocking completion callbacks work.

ppapi/thunk/ppb_udp_socket_private_api.h

 // Copyright (c) 2012 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_UDP_SOCKET_PRIVATE_API_H_
 #define PPAPI_THUNK_PPB_UDP_SOCKET_PRIVATE_API_H_
 
+#include "base/memory/ref_counted.h"
 #include "ppapi/c/private/ppb_udp_socket_private.h"
 #include "ppapi/thunk/ppapi_thunk_export.h"
 
 namespace ppapi {
+
+class TrackedCallback;
+
 namespace thunk {
 
 class PPAPI_THUNK_EXPORT PPB_UDPSocket_Private_API {
  public:
   virtual ~PPB_UDPSocket_Private_API() {}
 
   virtual int32_t Bind(const PP_NetAddress_Private* addr,
-                       PP_CompletionCallback callback) = 0;
+                       scoped_refptr<TrackedCallback> callback) = 0;
   virtual PP_Bool GetBoundAddress(PP_NetAddress_Private* addr) = 0;
   virtual int32_t RecvFrom(char* buffer,
                            int32_t num_bytes,
-                           PP_CompletionCallback callback) = 0;
+                           scoped_refptr<TrackedCallback> callback) = 0;
   virtual PP_Bool GetRecvFromAddress(PP_NetAddress_Private* addr) = 0;
   virtual int32_t SendTo(const char* buffer,
                          int32_t num_bytes,
                          const PP_NetAddress_Private* addr,
-                         PP_CompletionCallback callback) = 0;
+                         scoped_refptr<TrackedCallback> callback) = 0;
   virtual void Close() = 0;
 };
 
 }  // namespace thunk
 }  // namespace ppapi
 
 #endif  // PPAPI_THUNK_PPB_UDP_SOCKET_PRIVATE_API_H_