EDK: Add Core::DuplicateHandleWithReducedRights().

mojo/edk/system/shared_buffer_dispatcher.cc

 // Copyright 2014 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/edk/system/shared_buffer_dispatcher.h"
 
 #include <limits>
 #include <utility>
 
 #include "base/logging.h"
@@ skipping 201 matching lines @@
 
   return MOJO_RESULT_OK;
 }
 
 void SharedBufferDispatcher::CloseImplNoLock() {
   mutex().AssertHeld();
   DCHECK(shared_buffer_);
   shared_buffer_ = nullptr;
 }
 
+MojoResult SharedBufferDispatcher::DuplicateDispatcherImplNoLock(
+    util::RefPtr<Dispatcher>* new_dispatcher) {
+  mutex().AssertHeld();
+
+  // Note: Since this is "duplicate", we keep our ref to |shared_buffer_|.
+  *new_dispatcher = CreateInternal(shared_buffer_.Clone());
+  return MOJO_RESULT_OK;
+}
+
 RefPtr<Dispatcher>
 SharedBufferDispatcher::CreateEquivalentDispatcherAndCloseImplNoLock(
     MessagePipe* /*message_pipe*/,
     unsigned /*port*/) {
   mutex().AssertHeld();
 
   CancelAllAwakablesNoLock();
 
   DCHECK(shared_buffer_);
   return CreateInternal(std::move(shared_buffer_));
@@ skipping 98 matching lines @@
   platform_handles->push_back(std::move(platform_handle));
   *actual_size = sizeof(SerializedSharedBufferDispatcher);
 
   shared_buffer_ = nullptr;
 
   return true;
 }
 
 }  // namespace system
 }  // namespace mojo