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

mojo/system/message_pipe_endpoint.h

 // 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.
 
 #ifndef MOJO_SYSTEM_MESSAGE_PIPE_ENDPOINT_H_
 #define MOJO_SYSTEM_MESSAGE_PIPE_ENDPOINT_H_
 
 #include <stdint.h>
 
 #include <vector>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "mojo/public/c/system/message_pipe.h"
 #include "mojo/public/c/system/types.h"
 #include "mojo/system/dispatcher.h"
+#include "mojo/system/memory.h"
 #include "mojo/system/message_in_transit.h"
 #include "mojo/system/system_impl_export.h"
 
 namespace mojo {
 namespace system {
 
 class Channel;
 class Waiter;
 
 // This is an interface to one of the ends of a message pipe, and is used by
@@ skipping 26 matching lines @@
   // Implementations must override these if they represent a local endpoint,
   // i.e., one for which there's a |MessagePipeDispatcher| (and thus a handle).
   // An implementation for a proxy endpoint (for which there's no dispatcher)
   // needs not override these methods, since they should never be called.
   //
   // These methods implement the methods of the same name in |MessagePipe|,
   // though |MessagePipe|'s implementation may have to do a little more if the
   // operation involves both endpoints.
   virtual void Close();
   virtual void CancelAllWaiters();
-  virtual MojoResult ReadMessage(void* bytes,
-                                 uint32_t* num_bytes,
+  virtual MojoResult ReadMessage(UserPointer<void> bytes,
+                                 UserPointer<uint32_t> num_bytes,
                                  DispatcherVector* dispatchers,
                                  uint32_t* num_dispatchers,
                                  MojoReadMessageFlags flags);
   virtual MojoResult AddWaiter(Waiter* waiter,
                                MojoHandleSignals signals,
                                uint32_t context);
   virtual void RemoveWaiter(Waiter* waiter);
 
   // Implementations must override these if they represent a proxy endpoint. An
   // implementation for a local endpoint needs not override these methods, since
   // they should never be called.
   virtual void Attach(scoped_refptr<Channel> channel,
                       MessageInTransit::EndpointId local_id);
   // Returns false if the endpoint should be closed and destroyed, else true.
   virtual bool Run(MessageInTransit::EndpointId remote_id);
   virtual void OnRemove();
 
  protected:
   MessagePipeEndpoint() {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(MessagePipeEndpoint);
 };
 
 }  // namespace system
 }  // namespace mojo
 
 #endif  // MOJO_SYSTEM_MESSAGE_PIPE_ENDPOINT_H_