chromium/services/network/public/cpp/optional_trust_token_params.h

// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef SERVICES_NETWORK_PUBLIC_CPP_OPTIONAL_TRUST_TOKEN_PARAMS_H_
#define SERVICES_NETWORK_PUBLIC_CPP_OPTIONAL_TRUST_TOKEN_PARAMS_H_

#include <optional>

#include "base/component_export.h"
#include "services/network/public/mojom/trust_tokens.mojom.h"

namespace network {

// This class exists to wrap mojom::TrustTokenParamsPtr for use as a field in
// network::ResourceRequest.
//
// Motivation:
// 1. network::ResourceRequest has a requirement that all of
// network::ResourceRequest's members be trivially copyable;
// 2. Mojo struct pointers aren't, by default, trivially copyable;
// 3. Mojo only knows, from its generated code, how to serialize and deserialize
// struct pointers, not raw Mojo structs.
//
// One solution to this dilemma would be to manually define separate Mojo
// StructTraits for the raw struct type (network::mojom::TrustTokenParams), but
// this would add maintenance burden since it would require updating the traits
// every time the structure's definition changes.
//
// Using this trivially-copyable wrapper class (where the copy constructor and
// copy assignment operators use mojo::Clone) allows changing the format of the
// Mojo struct without having to manually update the corresponding
// serialization/deserialization code.
class COMPONENT_EXPORT(NETWORK_CPP_BASE) OptionalTrustTokenParams { … };

}  // namespace network

#endif  // SERVICES_NETWORK_PUBLIC_CPP_OPTIONAL_TRUST_TOKEN_PARAMS_H_