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

mojo/system/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/dispatcher.h"
 
 #include "base/logging.h"
 #include "mojo/system/constants.h"
 #include "mojo/system/message_pipe_dispatcher.h"
 #include "mojo/system/platform_handle_dispatcher.h"
@@ skipping 128 matching lines @@
 MojoResult Dispatcher::WriteData(const void* elements,
                                  uint32_t* num_bytes,
                                  MojoWriteDataFlags flags) {
   base::AutoLock locker(lock_);
   if (is_closed_)
     return MOJO_RESULT_INVALID_ARGUMENT;
 
   return WriteDataImplNoLock(elements, num_bytes, flags);
 }
 
-MojoResult Dispatcher::BeginWriteData(void** buffer,
-                                      uint32_t* buffer_num_bytes,
+MojoResult Dispatcher::BeginWriteData(UserPointer<void*> buffer,
+                                      UserPointer<uint32_t> buffer_num_bytes,
                                       MojoWriteDataFlags flags) {
   base::AutoLock locker(lock_);
   if (is_closed_)
     return MOJO_RESULT_INVALID_ARGUMENT;
 
   return BeginWriteDataImplNoLock(buffer, buffer_num_bytes, flags);
 }
 
 MojoResult Dispatcher::EndWriteData(uint32_t num_bytes_written) {
   base::AutoLock locker(lock_);
@@ skipping 117 matching lines @@
 
 MojoResult Dispatcher::WriteDataImplNoLock(const void* /*elements*/,
                                            uint32_t* /*num_bytes*/,
                                            MojoWriteDataFlags /*flags*/) {
   lock_.AssertAcquired();
   DCHECK(!is_closed_);
   // By default, not supported. Only needed for data pipe dispatchers.
   return MOJO_RESULT_INVALID_ARGUMENT;
 }
 
-MojoResult Dispatcher::BeginWriteDataImplNoLock(void** /*buffer*/,
-                                                uint32_t* /*buffer_num_bytes*/,
-                                                MojoWriteDataFlags /*flags*/) {
+MojoResult Dispatcher::BeginWriteDataImplNoLock(
+    UserPointer<void*> /*buffer*/,
+    UserPointer<uint32_t> /*buffer_num_bytes*/,
+    MojoWriteDataFlags /*flags*/) {
   lock_.AssertAcquired();
   DCHECK(!is_closed_);
   // By default, not supported. Only needed for data pipe dispatchers.
   return MOJO_RESULT_INVALID_ARGUMENT;
 }
 
 MojoResult Dispatcher::EndWriteDataImplNoLock(uint32_t /*num_bytes_written*/) {
   lock_.AssertAcquired();
   DCHECK(!is_closed_);
   // By default, not supported. Only needed for data pipe dispatchers.
@@ skipping 151 matching lines @@
 // DispatcherTransport ---------------------------------------------------------
 
 void DispatcherTransport::End() {
   DCHECK(dispatcher_);
   dispatcher_->lock_.Release();
   dispatcher_ = NULL;
 }
 
 }  // namespace system
 }  // namespace mojo