Add a new QuicFlagSaver class for saving/restoring the values of QUIC flags in tests.

net/quic/core/quic_crypto_server_stream_test.cc

 // Copyright (c) 2012 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 "net/quic/core/quic_crypto_server_stream.h"
 
 #include <map>
 #include <memory>
 #include <vector>
 
@@ skipping 153 matching lines @@
     CHECK(server_connection_);
     CHECK(client_session_ != nullptr);
 
     EXPECT_CALL(*client_session_, OnProofValid(_)).Times(testing::AnyNumber());
     client_stream()->CryptoConnect();
     CryptoTestUtils::AdvanceHandshake(client_connection_, client_stream(), 0,
                                       server_connection_, server_stream(), 0);
   }
 
  protected:
+  QuicFlagSaver flags_;  // Save/restore all QUIC flag values.
+
   // Every connection gets its own MockQuicConnectionHelper and
   // MockAlarmFactory,
   // tracked separately from
   // the server and client state so their lifetimes persist through the whole
   // test.
   std::vector<MockQuicConnectionHelper*> helpers_;
   std::vector<MockAlarmFactory*> alarm_factories_;
 
   // Server state
   PacketSavingConnection* server_connection_;
@@ skipping 56 matching lines @@
   InitializeFakeClient(/* supports_stateless_rejects= */ false);
 
   AdvanceHandshakeWithFakeClient();
   EXPECT_TRUE(server_stream()->encryption_established());
   EXPECT_TRUE(server_stream()->handshake_confirmed());
   EXPECT_EQ(ENCRYPTION_FORWARD_SECURE,
             server_session_->connection()->encryption_level());
 }
 
 TEST_P(QuicCryptoServerStreamTest, StatelessRejectAfterCHLO) {
-  ValueRestore<bool> old_flag(&FLAGS_enable_quic_stateless_reject_support,
-                              true);
+  FLAGS_enable_quic_stateless_reject_support = true;
+
   Initialize();
 
   EXPECT_CALL(*server_connection_,
               CloseConnection(QUIC_CRYPTO_HANDSHAKE_STATELESS_REJECT, _, _));
 
   InitializeFakeClient(/* supports_stateless_rejects= */ true);
   AdvanceHandshakeWithFakeClient();
 
   // Check the server to make the sure the handshake did not succeed.
   EXPECT_FALSE(server_stream()->encryption_established());
@@ skipping 12 matching lines @@
   const QuicConnectionId server_designated_connection_id =
       client_state->GetNextServerDesignatedConnectionId();
   const QuicConnectionId expected_id =
       server_connection_->random_generator()->RandUint64();
   EXPECT_EQ(expected_id, server_designated_connection_id);
   EXPECT_FALSE(client_state->has_server_designated_connection_id());
   ASSERT_TRUE(client_state->IsComplete(QuicWallTime::FromUNIXSeconds(0)));
 }
 
 TEST_P(QuicCryptoServerStreamTest, ConnectedAfterStatelessHandshake) {
-  ValueRestore<bool> old_flag(&FLAGS_enable_quic_stateless_reject_support,
-                              true);
+  FLAGS_enable_quic_stateless_reject_support = true;
+
   Initialize();
 
   InitializeFakeClient(/* supports_stateless_rejects= */ true);
   AdvanceHandshakeWithFakeClient();
 
   // On the first round, encryption will not be established.
   EXPECT_FALSE(server_stream()->encryption_established());
   EXPECT_FALSE(server_stream()->handshake_confirmed());
   EXPECT_EQ(1, server_stream()->NumHandshakeMessages());
   EXPECT_EQ(0, server_stream()->NumHandshakeMessagesWithServerNonces());
@@ skipping 23 matching lines @@
   AdvanceHandshakeWithFakeClient();
 
   // On the second round, encryption will be established.
   EXPECT_TRUE(server_stream()->encryption_established());
   EXPECT_TRUE(server_stream()->handshake_confirmed());
   EXPECT_EQ(1, server_stream()->NumHandshakeMessages());
   EXPECT_EQ(1, server_stream()->NumHandshakeMessagesWithServerNonces());
 }
 
 TEST_P(QuicCryptoServerStreamTest, NoStatelessRejectIfNoClientSupport) {
-  ValueRestore<bool> old_flag(&FLAGS_enable_quic_stateless_reject_support,
-                              true);
+  FLAGS_enable_quic_stateless_reject_support = true;
+
   Initialize();
 
   // The server is configured to use stateless rejects, but the client does not
   // support it.
   InitializeFakeClient(/* supports_stateless_rejects= */ false);
   AdvanceHandshakeWithFakeClient();
 
   // Check the server to make the sure the handshake did not succeed.
   EXPECT_FALSE(server_stream()->encryption_established());
   EXPECT_FALSE(server_stream()->handshake_confirmed());
@@ skipping 229 matching lines @@
       QUIC_NO_ERROR, "", ConnectionCloseBehavior::SILENT_CLOSE);
 
   // The outstanding nonce verification RPC now completes.
   strike_register_client_->RunPendingVerifications();
 }
 
 }  // namespace
 
 }  // namespace test
 }  // namespace net