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

net/quic/core/quic_server_session_base_test.cc

 // Copyright 2013 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_server_session_base.h"
 
 #include <cstdint>
 #include <memory>
 
 #include "base/macros.h"
@@ skipping 22 matching lines @@
 using net::test::MockQuicConnection;
 using net::test::MockQuicConnectionHelper;
 using net::test::QuicConfigPeer;
 using net::test::QuicConnectionPeer;
 using net::test::QuicSpdyStreamPeer;
 using net::test::QuicSentPacketManagerPeer;
 using net::test::QuicSessionPeer;
 using net::test::QuicSpdySessionPeer;
 using net::test::QuicSustainedBandwidthRecorderPeer;
 using net::test::SupportedVersions;
-using net::test::ValueRestore;
 using net::test::kClientDataStreamId1;
 using net::test::kClientDataStreamId2;
 using net::test::kClientDataStreamId3;
 using net::test::kInitialSessionFlowControlWindowForTest;
 using net::test::kInitialStreamFlowControlWindowForTest;
 using std::string;
 using testing::StrictMock;
 using testing::_;
 
 namespace net {
@@ skipping 502 matching lines @@
   EXPECT_FALSE(
       QuicServerSessionBasePeer::IsBandwidthResumptionEnabled(session_.get()));
   session_->OnConfigNegotiated();
   EXPECT_FALSE(
       QuicServerSessionBasePeer::IsBandwidthResumptionEnabled(session_.get()));
 }
 
 }  // namespace
 }  // namespace test
 }  // namespace net