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

mojo/system/message_pipe_dispatcher.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_dispatcher.h"
 
 #include "base/logging.h"
 #include "mojo/system/channel.h"
 #include "mojo/system/constants.h"
 #include "mojo/system/local_message_pipe_endpoint.h"
@@ skipping 180 matching lines @@
   if (!VerifyUserPointerWithSize<1>(bytes, num_bytes))
     return MOJO_RESULT_INVALID_ARGUMENT;
   if (num_bytes > kMaxMessageNumBytes)
     return MOJO_RESULT_RESOURCE_EXHAUSTED;
 
   return message_pipe_->WriteMessage(port_, bytes, num_bytes, transports,
                                      flags);
 }
 
 MojoResult MessagePipeDispatcher::ReadMessageImplNoLock(
-    void* bytes,
-    uint32_t* num_bytes,
+    UserPointer<void> bytes,
+    UserPointer<uint32_t> num_bytes,
     DispatcherVector* dispatchers,
     uint32_t* num_dispatchers,
     MojoReadMessageFlags flags) {
   lock().AssertAcquired();
-
-  if (num_bytes) {
-    if (!VerifyUserPointer<uint32_t>(num_bytes))
-      return MOJO_RESULT_INVALID_ARGUMENT;
-    if (!VerifyUserPointerWithSize<1>(bytes, *num_bytes))
-      return MOJO_RESULT_INVALID_ARGUMENT;
-  }
-
   return message_pipe_->ReadMessage(port_, bytes, num_bytes, dispatchers,
                                     num_dispatchers, flags);
 }
 
 MojoResult MessagePipeDispatcher::AddWaiterImplNoLock(Waiter* waiter,
                                                       MojoHandleSignals signals,
                                                       uint32_t context) {
   lock().AssertAcquired();
   return message_pipe_->AddWaiter(port_, waiter, signals, context);
 }
@@ skipping 47 matching lines @@
 
 // MessagePipeDispatcherTransport ----------------------------------------------
 
 MessagePipeDispatcherTransport::MessagePipeDispatcherTransport(
     DispatcherTransport transport) : DispatcherTransport(transport) {
   DCHECK_EQ(message_pipe_dispatcher()->GetType(), Dispatcher::kTypeMessagePipe);
 }
 
 }  // namespace system
 }  // namespace mojo