Make the fuchsia mojo/public repo the source of truth.

mojo/public/cpp/bindings/lib/callback_internal.h

-// 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.
-
-#ifndef MOJO_PUBLIC_CPP_BINDINGS_LIB_CALLBACK_INTERNAL_H_
-#define MOJO_PUBLIC_CPP_BINDINGS_LIB_CALLBACK_INTERNAL_H_
-
-#include "mojo/public/cpp/bindings/lib/template_util.h"
-
-namespace mojo {
-class String;
-
-namespace internal {
-
-template <typename T>
-struct Callback_ParamTraits {
-  typedef T ForwardType;
-};
-
-template <>
-struct Callback_ParamTraits<String> {
-  typedef const String& ForwardType;
-};
-
-}  // namespace internal
-}  // namespace mojo
-
-#endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_CALLBACK_INTERNAL_H_