Add a struct representing a Trust Tokens key commitment.

This is a minimal change adding a struct representing a Trust Tokens
key commitment registry's contents [1], with some slight variations
described in the Trust Tokens design doc (currently internal-only;
working to release a public version).

This is a common ancestor CL of trust token issuance, redemption,
and key commitment fetching and parsing.

[1]:
https://github.com/alxdavids/draft-privacy-pass/blob/master/draft-privacy-pass.md#key-registration-registry

Bug: 1042962
Change-Id: Ic0a20cb266c8133bb3545821b975e813bfb59c50
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2062674
Commit-Queue: David Van Cleve <davidvc@chromium.org>
Reviewed-by: Charlie Harrison <csharrison@chromium.org>
Cr-Commit-Position: refs/heads/master@{#742669}

services/network/trust_tokens/BUILD.gn

@@ -19,6 +19,8 @@ source_set("trust_tokens") {
     "trust_token_database_owner.cc",
     "trust_token_database_owner.h",
     "trust_token_http_headers.h",
+    "trust_token_key_commitment_result.cc",
+    "trust_token_key_commitment_result.h",
     "trust_token_operation_status.h",
     "trust_token_parameterization.h",
     "trust_token_persister.h",

services/network/trust_tokens/trust_token_key_commitment_result.cc

+// Copyright 2020 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.
+
+#include "services/network/trust_tokens/trust_token_key_commitment_result.h"
+
+#include <tuple>
+
+namespace network {
+
+TrustTokenKeyCommitmentResult::TrustTokenKeyCommitmentResult() = default;
+TrustTokenKeyCommitmentResult::~TrustTokenKeyCommitmentResult() = default;
+
+TrustTokenKeyCommitmentResult::TrustTokenKeyCommitmentResult(
+    const TrustTokenKeyCommitmentResult&) = default;
+TrustTokenKeyCommitmentResult::TrustTokenKeyCommitmentResult(
+    TrustTokenKeyCommitmentResult&&) = default;
+TrustTokenKeyCommitmentResult& TrustTokenKeyCommitmentResult::operator=(
+    const TrustTokenKeyCommitmentResult&) = default;
+TrustTokenKeyCommitmentResult& TrustTokenKeyCommitmentResult::operator=(
+    TrustTokenKeyCommitmentResult&&) = default;
+
+bool operator==(const TrustTokenKeyCommitmentResult::Key& lhs,
+                const TrustTokenKeyCommitmentResult::Key& rhs) {
+  return std::tie(lhs.body, lhs.expiry, lhs.label) ==
+         std::tie(rhs.body, rhs.expiry, rhs.label);
+}
+
+bool operator==(const TrustTokenKeyCommitmentResult& lhs,
+                const TrustTokenKeyCommitmentResult& rhs) {
+  return std::tie(lhs.batch_size, lhs.keys,
+                  lhs.signed_redemption_record_verification_key) ==
+         std::tie(rhs.batch_size, rhs.keys,
+                  rhs.signed_redemption_record_verification_key);
+}
+
+}  // namespace network

services/network/trust_tokens/trust_token_key_commitment_result.h

+// Copyright 2020 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 SERVICES_NETWORK_TRUST_TOKENS_TRUST_TOKEN_KEY_COMMITMENT_RESULT_H_
+#define SERVICES_NETWORK_TRUST_TOKENS_TRUST_TOKEN_KEY_COMMITMENT_RESULT_H_
+
+#include <string>
+#include <vector>
+
+#include "base/optional.h"
+#include "base/time/time.h"
+
+namespace network {
+
+// Struct TrustTokenKeyCommitmentResult represents a Trust Token issuer's
+// current key commitments and associated information provided through the key
+// commitment mechanism.
+struct TrustTokenKeyCommitmentResult final {
+  TrustTokenKeyCommitmentResult();
+  ~TrustTokenKeyCommitmentResult();
+
+  TrustTokenKeyCommitmentResult(const TrustTokenKeyCommitmentResult&);
+  TrustTokenKeyCommitmentResult(TrustTokenKeyCommitmentResult&&);
+
+  TrustTokenKeyCommitmentResult& operator=(
+      const TrustTokenKeyCommitmentResult&);
+  TrustTokenKeyCommitmentResult& operator=(TrustTokenKeyCommitmentResult&&);
+
+  struct Key {
+    std::string body;
+    base::Time expiry;
+    uint32_t label;
+  };
+  // |keys| is the collection of the issuer's current key commitments.
+  std::vector<Key> keys;
+
+  // |batch_size| is the issuer's optional number of tokens it wishes the client
+  // to request per Trust Tokens issuance operation.
+  base::Optional<int> batch_size;
+
+  // |signed_redemption_record_verification_key| is an Ed25519 public key that
+  // can be used to verify Signed Redemption Record (SRR) signatures
+  // subsequently provided by the issuer.
+  std::string signed_redemption_record_verification_key;
+};
+
+// For testing.
+bool operator==(const TrustTokenKeyCommitmentResult::Key& lhs,
+                const TrustTokenKeyCommitmentResult::Key& rhs);
+bool operator==(const TrustTokenKeyCommitmentResult& lhs,
+                const TrustTokenKeyCommitmentResult& rhs);
+
+}  // namespace network
+
+#endif  // SERVICES_NETWORK_TRUST_TOKENS_TRUST_TOKEN_KEY_COMMITMENT_RESULT_H_