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

mojo/edk/system/mock_simple_dispatcher.h

 // Copyright 2016 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_MOCK_SIMPLE_DISPATCHER_H_
 #define MOJO_EDK_SYSTEM_MOCK_SIMPLE_DISPATCHER_H_
 
 #include "mojo/edk/system/handle_signals_state.h"
 #include "mojo/edk/system/simple_dispatcher.h"
 #include "mojo/edk/util/thread_annotations.h"
@@ skipping 19 matching lines @@
  private:
   FRIEND_MAKE_REF_COUNTED(MockSimpleDispatcher);
 
   MockSimpleDispatcher(
       MojoHandleSignals satisfied_signals = MOJO_HANDLE_SIGNAL_NONE,
       MojoHandleSignals satisfiable_signals = MOJO_HANDLE_SIGNAL_READABLE |
                                               MOJO_HANDLE_SIGNAL_WRITABLE);
   explicit MockSimpleDispatcher(const HandleSignalsState& state);
   ~MockSimpleDispatcher() override;
 
-  util::RefPtr<Dispatcher> CreateEquivalentDispatcherAndCloseImplNoLock()
-      override;
+  util::RefPtr<Dispatcher> CreateEquivalentDispatcherAndCloseImplNoLock(
+      MessagePipe* message_pipe,
+      unsigned port) override;
 
   // |Dispatcher| override:
   HandleSignalsState GetHandleSignalsStateImplNoLock() const override;
 
   HandleSignalsState state_ MOJO_GUARDED_BY(mutex());
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(MockSimpleDispatcher);
 };
 
 }  // namespace test
 }  // namespace system
 }  // namespace mojo
 
 #endif  // MOJO_EDK_SYSTEM_MOCK_SIMPLE_DISPATCHER_H_