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

mojo/system/dispatcher.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_DISPATCHER_H_
 #define MOJO_SYSTEM_DISPATCHER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <vector>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/synchronization/lock.h"
 #include "mojo/embedder/platform_handle.h"
 #include "mojo/embedder/platform_handle_vector.h"
 #include "mojo/public/c/system/buffer.h"
 #include "mojo/public/c/system/data_pipe.h"
 #include "mojo/public/c/system/message_pipe.h"
 #include "mojo/public/c/system/types.h"
+#include "mojo/system/memory.h"
 #include "mojo/system/system_impl_export.h"
 
 namespace mojo {
 namespace system {
 
 class Channel;
 class Core;
 class Dispatcher;
 class DispatcherTransport;
 class HandleTable;
@@ skipping 54 matching lines @@
   // and nonzero. On success, it will be set to the dispatchers to be received
   // (and assigned handles) as part of the message.
   MojoResult ReadMessage(void* bytes,
                          uint32_t* num_bytes,
                          DispatcherVector* dispatchers,
                          uint32_t* num_dispatchers,
                          MojoReadMessageFlags flags);
   MojoResult WriteData(const void* elements,
                        uint32_t* elements_num_bytes,
                        MojoWriteDataFlags flags);
-  MojoResult BeginWriteData(void** buffer,
-                            uint32_t* buffer_num_bytes,
+  MojoResult BeginWriteData(UserPointer<void*> buffer,
+                            UserPointer<uint32_t> buffer_num_bytes,
                             MojoWriteDataFlags flags);
   MojoResult EndWriteData(uint32_t num_bytes_written);
   MojoResult ReadData(void* elements,
                       uint32_t* num_bytes,
                       MojoReadDataFlags flags);
   MojoResult BeginReadData(const void** buffer,
                            uint32_t* buffer_num_bytes,
                            MojoReadDataFlags flags);
   MojoResult EndReadData(uint32_t num_bytes_read);
   // |options| may be null. |new_dispatcher| must not be null, but
@@ skipping 108 matching lines @@
       std::vector<DispatcherTransport>* transports,
       MojoWriteMessageFlags flags);
   virtual MojoResult ReadMessageImplNoLock(void* bytes,
                                            uint32_t* num_bytes,
                                            DispatcherVector* dispatchers,
                                            uint32_t* num_dispatchers,
                                            MojoReadMessageFlags flags);
   virtual MojoResult WriteDataImplNoLock(const void* elements,
                                          uint32_t* num_bytes,
                                          MojoWriteDataFlags flags);
-  virtual MojoResult BeginWriteDataImplNoLock(void** buffer,
-                                              uint32_t* buffer_num_bytes,
-                                              MojoWriteDataFlags flags);
+  virtual MojoResult BeginWriteDataImplNoLock(
+      UserPointer<void*> buffer,
+      UserPointer<uint32_t> buffer_num_bytes,
+      MojoWriteDataFlags flags);
   virtual MojoResult EndWriteDataImplNoLock(uint32_t num_bytes_written);
   virtual MojoResult ReadDataImplNoLock(void* elements,
                                         uint32_t* num_bytes,
                                         MojoReadDataFlags flags);
   virtual MojoResult BeginReadDataImplNoLock(const void** buffer,
                                              uint32_t* buffer_num_bytes,
                                              MojoReadDataFlags flags);
   virtual MojoResult EndReadDataImplNoLock(uint32_t num_bytes_read);
   virtual MojoResult DuplicateBufferHandleImplNoLock(
       const MojoDuplicateBufferHandleOptions* options,
@@ skipping 130 matching lines @@
 
   Dispatcher* dispatcher_;
 
   // Copy and assign allowed.
 };
 
 }  // namespace system
 }  // namespace mojo
 
 #endif  // MOJO_SYSTEM_DISPATCHER_H_