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

mojo/public/cpp/bindings/lib/message_header_validator.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_MESSAGE_HEADER_VALIDATOR_H_
-#define MOJO_PUBLIC_CPP_BINDINGS_LIB_MESSAGE_HEADER_VALIDATOR_H_
-
-#include <string>
-
-#include "mojo/public/cpp/bindings/lib/validation_errors.h"
-#include "mojo/public/cpp/bindings/message_validator.h"
-
-namespace mojo {
-namespace internal {
-
-class MessageHeaderValidator final : public MessageValidator {
- public:
-  ValidationError Validate(const Message* message, std::string* err) override;
-};
-
-// The following methods validate control messages defined in
-// interface_control_messages.mojom.
-ValidationError ValidateControlRequest(const Message* message,
-                                       std::string* err);
-ValidationError ValidateControlResponse(const Message* message,
-                                        std::string* err);
-
-}  // namespace internal
-}  // namespace mojo
-
-#endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_MESSAGE_HEADER_VALIDATOR_H_