Convert ReadMessage...() to use the new user pointer handling (see r285350).

mojo/system/message_pipe.cc

 // Copyright 2013 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 "mojo/system/message_pipe.h"
 
 #include "base/logging.h"
 #include "mojo/system/channel.h"
 #include "mojo/system/local_message_pipe_endpoint.h"
 #include "mojo/system/message_in_transit.h"
@@ skipping 65 matching lines @@
       GetPeerPort(port),
       make_scoped_ptr(new MessageInTransit(
           MessageInTransit::kTypeMessagePipeEndpoint,
           MessageInTransit::kSubtypeMessagePipeEndpointData,
           num_bytes,
           bytes)),
       transports);
 }
 
 MojoResult MessagePipe::ReadMessage(unsigned port,
-                                    void* bytes,
-                                    uint32_t* num_bytes,
+                                    UserPointer<void> bytes,
+                                    UserPointer<uint32_t> num_bytes,
                                     DispatcherVector* dispatchers,
                                     uint32_t* num_dispatchers,
                                     MojoReadMessageFlags flags) {
   DCHECK(port == 0 || port == 1);
 
   base::AutoLock locker(lock_);
   DCHECK(endpoints_[port]);
 
   return endpoints_[port]->ReadMessage(bytes, num_bytes, dispatchers,
                                        num_dispatchers, flags);
@@ skipping 178 matching lines @@
 MojoResult MessagePipe::HandleControlMessage(
     unsigned /*port*/,
     scoped_ptr<MessageInTransit> message) {
   LOG(WARNING) << "Unrecognized MessagePipe control message subtype "
                << message->subtype();
   return MOJO_RESULT_UNKNOWN;
 }
 
 }  // namespace system
 }  // namespace mojo