Move optional.h to webrtc/api/

webrtc/modules/audio_processing/aec3/matched_filter_lag_aggregator.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.
  */
 
 #ifndef WEBRTC_MODULES_AUDIO_PROCESSING_AEC3_MATCHED_FILTER_LAG_AGGREGATOR_H_
 #define WEBRTC_MODULES_AUDIO_PROCESSING_AEC3_MATCHED_FILTER_LAG_AGGREGATOR_H_
 
 #include <vector>
 
+#include "webrtc/api/optional.h"
 #include "webrtc/modules/audio_processing/aec3/matched_filter.h"
 #include "webrtc/rtc_base/constructormagic.h"
-#include "webrtc/rtc_base/optional.h"
 
 namespace webrtc {
 
 class ApmDataDumper;
 
 // Aggregates lag estimates produced by the MatchedFilter class into a single
 // reliable combined lag estimate.
 class MatchedFilterLagAggregator {
  public:
   MatchedFilterLagAggregator(ApmDataDumper* data_dumper,
@@ skipping 11 matching lines @@
   ApmDataDumper* const data_dumper_;
   std::vector<size_t> lag_updates_in_a_row_;
   size_t candidate_ = 0;
   size_t candidate_counter_ = 0;
 
   RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(MatchedFilterLagAggregator);
 };
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_AUDIO_PROCESSING_AEC3_MATCHED_FILTER_LAG_AGGREGATOR_H_