mac: Add auto-close and share-read-only functionality to SharedMemory.

ipc/ipc_message_utils.cc

 // Copyright (c) 2012 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 "ipc/ipc_message_utils.h"
 
 #include "base/files/file_path.h"
 #include "base/json/json_writer.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/strings/nullable_string16.h"
@@ skipping 545 matching lines @@
     case base::SharedMemoryHandle::POSIX:
       ParamTraits<base::FileDescriptor>::Write(m, p.GetFileDescriptor());
       break;
     case base::SharedMemoryHandle::MACH:
       MachPortMac mach_port_mac(p.GetMemoryObject());
       ParamTraits<MachPortMac>::Write(m, mach_port_mac);
       size_t size = 0;
       bool result = p.GetSize(&size);
       DCHECK(result);
       ParamTraits<size_t>::Write(m, size);
+
+      // If the caller intended to pass ownership to the IPC stack, release a
+      // reference.
+      if (p.OwnershipPassesToIPC())
+        p.Close();
+
       break;
   }
 }
 
 bool ParamTraits<base::SharedMemoryHandle>::Read(const Message* m,
                                                  base::PickleIterator* iter,
                                                  param_type* r) {
   base::SharedMemoryHandle::TypeWireFormat type;
   if (!iter->ReadInt(&type))
     return false;
@@ skipping 457 matching lines @@
   return result;
 }
 
 void ParamTraits<MSG>::Log(const param_type& p, std::string* l) {
   l->append("<MSG>");
 }
 
 #endif  // OS_WIN
 
 }  // namespace IPC