Pepper SRPC proxy style and type nits

ppapi/native_client/src/shared/ppapi_proxy/browser_ppp_messaging.cc

 // 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.
 
 #include "native_client/src/shared/ppapi_proxy/browser_ppp_messaging.h"
 
 #include "native_client/src/include/nacl_scoped_ptr.h"
 #include "native_client/src/shared/ppapi_proxy/browser_globals.h"
 #include "native_client/src/shared/ppapi_proxy/object_serialize.h"
 #include "native_client/src/shared/ppapi_proxy/utility.h"
 #include "ppapi/c/pp_instance.h"
 #include "ppapi/c/pp_var.h"
 #include "srpcgen/ppp_rpc.h"
 
 namespace ppapi_proxy {
 
 namespace {
 
 void HandleMessage(PP_Instance instance, struct PP_Var message) {
-  DebugPrintf("PPP_Messaging::HandleMessage: instance=%"NACL_PRIu32"\n",
+  DebugPrintf("PPP_Messaging::HandleMessage: instance=%"NACL_PRId32"\n",
               instance);
   uint32_t message_length = 0;
   nacl::scoped_array<char> message_bytes(Serialize(&message, 1,
                                                    &message_length));
   NaClSrpcError srpc_result =
       PppMessagingRpcClient::PPP_Messaging_HandleMessage(
           GetMainSrpcChannel(instance),
           instance,
           message_length,
           message_bytes.get());
 
   DebugPrintf("PPP_Messaging::HandleMessage: %s\n",
               NaClSrpcErrorString(srpc_result));
 }
 
 }  // namespace
 
 const PPP_Messaging* BrowserMessaging::GetInterface() {
   static const PPP_Messaging messaging_interface = {
     HandleMessage
   };
   return &messaging_interface;
 }
 
 }  // namespace ppapi_proxy