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

mojo/system/data_pipe.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_DATA_PIPE_H_
 #define MOJO_SYSTEM_DATA_PIPE_H_
 
 #include <stdint.h>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/synchronization/lock.h"
 #include "mojo/public/c/system/data_pipe.h"
 #include "mojo/public/c/system/types.h"
 #include "mojo/system/handle_signals_state.h"
+#include "mojo/system/memory.h"
 #include "mojo/system/system_impl_export.h"
 
 namespace mojo {
 namespace system {
 
 class Waiter;
 class WaiterList;
 
 // |DataPipe| is a base class for secondary objects implementing data pipes,
 // similar to |MessagePipe| (see the explanatory comment in core.cc). It is
@@ skipping 20 matching lines @@
 
   // These are called by the producer dispatcher to implement its methods of
   // corresponding names.
   void ProducerCancelAllWaiters();
   void ProducerClose();
   // This does not validate its arguments, except to check that |*num_bytes| is
   // a multiple of |element_num_bytes_|.
   MojoResult ProducerWriteData(const void* elements,
                                uint32_t* num_bytes,
                                bool all_or_none);
-  // This does not validate its arguments.
-  MojoResult ProducerBeginWriteData(void** buffer,
-                                    uint32_t* buffer_num_bytes,
+  MojoResult ProducerBeginWriteData(UserPointer<void*> buffer,
+                                    UserPointer<uint32_t> buffer_num_bytes,
                                     bool all_or_none);
   MojoResult ProducerEndWriteData(uint32_t num_bytes_written);
   MojoResult ProducerAddWaiter(Waiter* waiter,
                                MojoHandleSignals signals,
                                uint32_t context);
   void ProducerRemoveWaiter(Waiter* waiter);
   bool ProducerIsBusy() const;
 
   // These are called by the consumer dispatcher to implement its methods of
   // corresponding names.
@@ skipping 25 matching lines @@
 
   friend class base::RefCountedThreadSafe<DataPipe>;
   virtual ~DataPipe();
 
   virtual void ProducerCloseImplNoLock() = 0;
   // |*num_bytes| will be a nonzero multiple of |element_num_bytes_|.
   virtual MojoResult ProducerWriteDataImplNoLock(const void* elements,
                                                  uint32_t* num_bytes,
                                                  bool all_or_none) = 0;
   virtual MojoResult ProducerBeginWriteDataImplNoLock(
-      void** buffer,
-      uint32_t* buffer_num_bytes,
-      bool all_or_none) = 0;
+      UserPointer<void*> buffer,
+      UserPointer<uint32_t> buffer_num_bytes,
+      uint32_t min_num_bytes_to_write) = 0;
   virtual MojoResult ProducerEndWriteDataImplNoLock(
       uint32_t num_bytes_written) = 0;
   // Note: A producer should not be writable during a two-phase write.
   virtual HandleSignalsState ProducerGetHandleSignalsStateNoLock() const = 0;
 
   virtual void ConsumerCloseImplNoLock() = 0;
   // |*num_bytes| will be a nonzero multiple of |element_num_bytes_|.
   virtual MojoResult ConsumerReadDataImplNoLock(void* elements,
                                                 uint32_t* num_bytes,
                                                 bool all_or_none) = 0;
@@ skipping 78 matching lines @@
   uint32_t producer_two_phase_max_num_bytes_written_;
   uint32_t consumer_two_phase_max_num_bytes_read_;
 
   DISALLOW_COPY_AND_ASSIGN(DataPipe);
 };
 
 }  // namespace system
 }  // namespace mojo
 
 #endif  // MOJO_SYSTEM_DATA_PIPE_H_