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

net/quic/core/quic_headers_stream_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_headers_stream.h"
 
 #include <string>
 
 #include "base/strings/string_number_conversions.h"
 #include "net/quic/core/quic_bug_tracker.h"
@@ skipping 363 matching lines @@
 
   void TearDownLocalConnectionState() {
     QuicConnectionPeer::TearDownLocalConnectionState(connection_);
   }
 
   QuicStreamId NextPromisedStreamId() { return next_promised_stream_id_ += 2; }
 
   static const bool kFrameComplete = true;
   static const bool kHasPriority = true;
 
+  QuicFlagSaver flags_;  // Save/restore all QUIC flag values.
   const TestParams test_params_;
   MockQuicConnectionHelper helper_;
   MockAlarmFactory alarm_factory_;
   StrictMock<MockQuicConnection>* connection_;
   StrictMock<MockQuicSpdySession> session_;
   QuicHeadersStream* headers_stream_;
   SpdyHeaderBlock headers_;
   std::unique_ptr<TestHeadersHandler> headers_handler_;
   string body_;
   string saved_data_;
@@ skipping 568 matching lines @@
       }
       saved_data_.clear();
       saved_payloads_.clear();
     }
   }
 }
 
 }  // namespace
 }  // namespace test
 }  // namespace net