Move optional.h to webrtc/api/

webrtc/call/syncable.h

 /*
  *  Copyright (c) 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.
  */
 
 // Syncable is used by RtpStreamsSynchronizer in VideoReceiveStream, and
 // implemented by AudioReceiveStream.
 
 #ifndef WEBRTC_CALL_SYNCABLE_H_
 #define WEBRTC_CALL_SYNCABLE_H_
 
 #include <stdint.h>
 
-#include "webrtc/rtc_base/optional.h"
+#include "webrtc/api/optional.h"
 
 namespace webrtc {
 
 class Syncable {
  public:
   struct Info {
     int64_t latest_receive_time_ms = 0;
     uint32_t latest_received_capture_timestamp = 0;
     uint32_t capture_time_ntp_secs = 0;
     uint32_t capture_time_ntp_frac = 0;
     uint32_t capture_time_source_clock = 0;
     int current_delay_ms = 0;
   };
 
   virtual ~Syncable();
 
   virtual int id() const = 0;
   virtual rtc::Optional<Info> GetInfo() const = 0;
   virtual uint32_t GetPlayoutTimestamp() const = 0;
   virtual void SetMinimumPlayoutDelay(int delay_ms) = 0;
 };
 }  // namespace webrtc
 
 #endif  // WEBRTC_CALL_SYNCABLE_H_