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

mojo/system/core.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/core.h"
 
 #include <vector>
 
 #include "base/logging.h"
 #include "base/time/time.h"
@@ skipping 255 matching lines @@
                              MojoReadMessageFlags flags) {
   scoped_refptr<Dispatcher> dispatcher(GetDispatcher(message_pipe_handle));
   if (!dispatcher)
     return MOJO_RESULT_INVALID_ARGUMENT;
 
   uint32_t num_handles_value = num_handles.IsNull() ? 0 : num_handles.Get();
 
   MojoResult rv;
   if (num_handles_value == 0) {
     // Easy case: won't receive any handles.
-    rv = dispatcher->ReadMessage(bytes.GetPointerUnsafe(),
-                                 num_bytes.GetPointerUnsafe(), NULL,
-                                 &num_handles_value, flags);
+    rv = dispatcher->ReadMessage(bytes, num_bytes, NULL, &num_handles_value,
+                                 flags);
   } else {
     DispatcherVector dispatchers;
-    rv = dispatcher->ReadMessage(bytes.GetPointerUnsafe(),
-                                 num_bytes.GetPointerUnsafe(), &dispatchers,
+    rv = dispatcher->ReadMessage(bytes, num_bytes, &dispatchers,
                                  &num_handles_value, flags);
     if (!dispatchers.empty()) {
       DCHECK_EQ(rv, MOJO_RESULT_OK);
       DCHECK(!num_handles.IsNull());
       DCHECK_LE(dispatchers.size(), static_cast<size_t>(num_handles_value));
 
       bool success;
       UserPointer<MojoHandle>::Writer handles_writer(handles,
                                                      dispatchers.size());
       {
@@ skipping 268 matching lines @@
   // |Wait()|/|WaitMany()| call. (Only after doing this can |waiter| be
   // destroyed, but this would still be required if the waiter were in TLS.)
   for (i = 0; i < num_added; i++)
     dispatchers[i]->RemoveWaiter(&waiter);
 
   return rv;
 }
 
 }  // namespace system
 }  // namespace mojo