Move optional.h to webrtc/api/

webrtc/rtc_tools/network_tester/config_reader.h

 /*
  *  Copyright 2017 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #ifndef WEBRTC_RTC_TOOLS_NETWORK_TESTER_CONFIG_READER_H_
 #define WEBRTC_RTC_TOOLS_NETWORK_TESTER_CONFIG_READER_H_
 
 #include <fstream>
 #include <string>
 
+#include "webrtc/api/optional.h"
 #include "webrtc/rtc_base/constructormagic.h"
-#include "webrtc/rtc_base/optional.h"
 
 #include "webrtc/rtc_base/ignore_wundef.h"
 
 #ifdef WEBRTC_NETWORK_TESTER_PROTO
 RTC_PUSH_IGNORING_WUNDEF()
 #include "webrtc/rtc_tools/network_tester/network_tester_config.pb.h"
 RTC_POP_IGNORING_WUNDEF()
 using webrtc::network_tester::config::NetworkTesterAllConfigs;
 #else
 class NetworkTesterConfigs;
@@ skipping 15 matching lines @@
 
  private:
   NetworkTesterAllConfigs proto_all_configs_;
   int proto_config_index_;
   RTC_DISALLOW_COPY_AND_ASSIGN(ConfigReader);
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_RTC_TOOLS_NETWORK_TESTER_CONFIG_READER_H_