PPAPI: Make blocking completion callbacks work.

ppapi/thunk/ppb_tcp_server_socket_private_api.h

Index: ppapi/thunk/ppb_tcp_server_socket_private_api.h
diff --git a/ppapi/thunk/ppb_tcp_server_socket_private_api.h b/ppapi/thunk/ppb_tcp_server_socket_private_api.h
index b88dfc8bb661de214d7ffa519eb64f933cb1af86..8563bef2cb8d8fced4baa7dc93cbc1baf5a745dc 100644
--- a/ppapi/thunk/ppb_tcp_server_socket_private_api.h
+++ b/ppapi/thunk/ppb_tcp_server_socket_private_api.h
@@ -5,10 +5,14 @@
 #ifndef PPAPI_THUNK_PPB_TCP_SERVER_SOCKET_PRIVATE_API_H_
 #define PPAPI_THUNK_PPB_TCP_SERVER_SOCKET_PRIVATE_API_H_
 
+#include "base/memory/ref_counted.h"
 #include "ppapi/c/private/ppb_tcp_server_socket_private.h"
 #include "ppapi/thunk/ppapi_thunk_export.h"
 
 namespace ppapi {
+
+class TrackedCallback;
+
 namespace thunk {
 
 class PPAPI_THUNK_EXPORT PPB_TCPServerSocket_Private_API {
@@ -17,9 +21,9 @@ public:
 
   virtual int32_t Listen(const PP_NetAddress_Private* addr,
                          int32_t backlog,
-                         PP_CompletionCallback callback) = 0;
+                         scoped_refptr<TrackedCallback> callback) = 0;
   virtual int32_t Accept(PP_Resource* tcp_socket,
-                         PP_CompletionCallback callback) = 0;
+                         scoped_refptr<TrackedCallback> callback) = 0;
   virtual void StopListening() = 0;
 };