Convert resources to take an instance key instead of an Instance*.

ppapi/cpp/private/udp_socket_private.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_CPP_PRIVATE_UDP_SOCKET_PRIVATE_H_
 #define PPAPI_CPP_PRIVATE_UDP_SOCKET_PRIVATE_H_
 
 #include "ppapi/c/pp_stdint.h"
 #include "ppapi/c/private/ppb_udp_socket_private.h"
 #include "ppapi/cpp/resource.h"
 
 namespace pp {
 
 class CompletionCallback;
-class Instance;
+class InstanceHandle;
 
 class UDPSocketPrivate : public Resource {
  public:
-  explicit UDPSocketPrivate(Instance* instance);
+  explicit UDPSocketPrivate(const InstanceHandle& instance);
 
   int32_t Bind(const PP_NetAddress_Private* addr,
                const CompletionCallback& callback);
   int32_t RecvFrom(char* buffer,
                    int32_t num_bytes,
                    const CompletionCallback& callback);
   bool GetRecvFromAddress(PP_NetAddress_Private* addr);
   int32_t SendTo(const char* buffer,
                  int32_t num_bytes,
                  const PP_NetAddress_Private* addr,
                  const CompletionCallback& callback);
   void Close();
 };
 
 }  // namespace pp
 
 #endif  // PPAPI_CPP_PRIVATE_UDP_SOCKET_PRIVATE_H_