mus: Add support for sending IOSurface mach_ports over mojo.

mojo/public/cpp/system/platform_handle.h

Index: mojo/public/cpp/system/platform_handle.h
diff --git a/mojo/public/cpp/system/platform_handle.h b/mojo/public/cpp/system/platform_handle.h
index 4e33f1b1baf3e0a321feb3ba969191ea95898fd8..801264efce650c69d39f798b4f4b37cd5f08e296 100644
--- a/mojo/public/cpp/system/platform_handle.h
+++ b/mojo/public/cpp/system/platform_handle.h
@@ -76,6 +76,17 @@ UnwrapSharedMemoryHandle(ScopedSharedBufferHandle 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_