Move optional.h to webrtc/api/

webrtc/video/quality_threshold.h

 /*
  *  Copyright (c) 2016 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_VIDEO_QUALITY_THRESHOLD_H_
 #define WEBRTC_VIDEO_QUALITY_THRESHOLD_H_
 
 #include <memory>
 
-#include "webrtc/rtc_base/optional.h"
+#include "webrtc/api/optional.h"
 
 namespace webrtc {
 
 class QualityThreshold {
  public:
   // Both thresholds are inclusive, i.e. measurement >= high signifies a high
   // state, while measurement <= low signifies a low state.
   QualityThreshold(int low_threshold,
                    int high_threshold,
                    float fraction,
@@ skipping 16 matching lines @@
   int sum_;
   int count_low_;
   int count_high_;
   int num_high_states_;
   int num_certain_states_;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_VIDEO_QUALITY_THRESHOLD_H_