Make it possible to write a message pipe endpoint's peer into it.

mojo/edk/system/data_pipe_producer_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_EDK_SYSTEM_DATA_PIPE_PRODUCER_DISPATCHER_H_
 #define MOJO_EDK_SYSTEM_DATA_PIPE_PRODUCER_DISPATCHER_H_
 
 #include "mojo/edk/system/dispatcher.h"
 #include "mojo/edk/util/ref_ptr.h"
 #include "mojo/edk/util/thread_annotations.h"
@@ skipping 28 matching lines @@
   // Get access to the |DataPipe| for testing.
   DataPipe* GetDataPipeForTest();
 
  private:
   DataPipeProducerDispatcher();
   ~DataPipeProducerDispatcher() override;
 
   // |Dispatcher| protected methods:
   void CancelAllAwakablesNoLock() override;
   void CloseImplNoLock() override;
-  util::RefPtr<Dispatcher> CreateEquivalentDispatcherAndCloseImplNoLock()
-      override;
+  util::RefPtr<Dispatcher> CreateEquivalentDispatcherAndCloseImplNoLock(
+      MessagePipe* message_pipe,
+      unsigned port) override;
   MojoResult SetDataPipeProducerOptionsImplNoLock(
       UserPointer<const MojoDataPipeProducerOptions> options) override;
   MojoResult GetDataPipeProducerOptionsImplNoLock(
       UserPointer<MojoDataPipeProducerOptions> options,
       uint32_t options_num_bytes) override;
   MojoResult WriteDataImplNoLock(UserPointer<const void> elements,
                                  UserPointer<uint32_t> num_bytes,
                                  MojoWriteDataFlags flags) override;
   MojoResult BeginWriteDataImplNoLock(UserPointer<void*> buffer,
                                       UserPointer<uint32_t> buffer_num_bytes,
@@ skipping 21 matching lines @@
   // This will be null if closed.
   util::RefPtr<DataPipe> data_pipe_ MOJO_GUARDED_BY(mutex());
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(DataPipeProducerDispatcher);
 };
 
 }  // namespace system
 }  // namespace mojo
 
 #endif  // MOJO_EDK_SYSTEM_DATA_PIPE_PRODUCER_DISPATCHER_H_