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

net/quic/chromium/quic_network_transaction_unittest.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 <memory>
 #include <ostream>
 #include <string>
 #include <utility>
 #include <vector>
 
@@ skipping 647 matching lines @@
     EXPECT_TRUE(session_->proxy_service()->proxy_retry_info().empty());
 
     // The alternative proxy server should no longer be in use.
     EXPECT_FALSE(test_proxy_delegate.alternative_proxy_server().is_valid());
 
     // Verify that the second request completes successfully, and the
     // alternative proxy server job is not started.
     SendRequestAndExpectHttpResponseFromProxy("hello from http", true, 443);
   }
 
+  QuicFlagSaver flags_;  // Save/restore all QUIC flag values.
   MockClock* clock_;  // Owned by QuicStreamFactory after CreateSession.
   QuicTestPacketMaker client_maker_;
   QuicTestPacketMaker server_maker_;
   std::unique_ptr<HttpNetworkSession> session_;
   MockClientSocketFactory socket_factory_;
   ProofVerifyDetailsChromium verify_details_;
   MockCryptoClientStreamFactory crypto_client_stream_factory_;
   MockHostResolver host_resolver_;
   MockCertVerifier cert_verifier_;
   TransportSecurityState transport_security_state_;
@@ skipping 1874 matching lines @@
   EXPECT_LT(0u, entries.size());
 
   // Check that we logged a QUIC_HTTP_STREAM_ADOPTED_PUSH_STREAM
   int pos = ExpectLogContainsSomewhere(
       entries, 0, NetLog::TYPE_QUIC_HTTP_STREAM_ADOPTED_PUSH_STREAM,
       NetLog::PHASE_NONE);
   EXPECT_LT(0, pos);
 }
 
 TEST_P(QuicNetworkTransactionTest, QuicForceHolBlocking) {
-  ValueRestore<bool> old_v35_flag(&FLAGS_quic_enable_version_35,
-                                  FLAGS_quic_enable_version_35);
-  ValueRestore<bool> old_v36_flag(&FLAGS_quic_enable_version_36,
-                                  FLAGS_quic_enable_version_36);
   FLAGS_quic_enable_version_35 = true;
   FLAGS_quic_enable_version_36 = true;
   params_.quic_force_hol_blocking = true;
   params_.origins_to_force_quic_on.insert(
       HostPortPair::FromString("mail.example.org:443"));
 
   MockQuicData mock_quic_data;
 
   QuicStreamOffset offset = 0;
   mock_quic_data.AddWrite(ConstructClientRequestHeadersPacket(
@@ skipping 451 matching lines @@
   AddHangingSocketData();
 
   SendRequestAndExpectQuicResponse(origin1_);
   SendRequestAndExpectQuicResponse(origin2_);
 
   EXPECT_TRUE(AllDataConsumed());
 }
 
 }  // namespace test
 }  // namespace net