mus: Add support for sending IOSurface mach_ports over mojo.

mojo/public/cpp/system/platform_handle.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.
 
 // This file provides a C++ wrapping around the Mojo C API for platform handles,
 // replacing the prefix of "Mojo" with a "mojo" namespace.
 //
 // Please see "mojo/public/c/system/platform_handle.h" for complete
 // documentation of the API.
 
@@ skipping 58 matching lines @@
     bool read_only);
 
 // Unwraps a base::SharedMemoryHandle from a Mojo handle. The caller assumes
 // responsibility for the lifetime of the SharedMemoryHandle.
 MOJO_CPP_SYSTEM_EXPORT MojoResult
 UnwrapSharedMemoryHandle(ScopedSharedBufferHandle handle,
                          base::SharedMemoryHandle* memory_handle,
                          size_t* size,
                          bool* read_only);
 
+#if defined(OS_MACOSX) && !defined(OS_IOS)
+// Wraps a mach_port_t as a Mojo handle. This takes a reference to the
+// Mach port.
+MOJO_CPP_SYSTEM_EXPORT ScopedHandle WrapMachPort(mach_port_t port);
+
+// Unwraps a mach_port_t from a Mojo handle. The caller gets ownership of the
+// Mach port.
+MOJO_CPP_SYSTEM_EXPORT MojoResult UnwrapMachPort(ScopedHandle handle,
+                                                 mach_port_t* port);
+#endif  // defined(OS_MACOSX) && !defined(OS_IOS)
+
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_SYSTEM_PLATFORM_HANDLE_H_