Move optional.h to webrtc/api/

webrtc/modules/audio_processing/aec3/echo_path_delay_estimator.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_ECHO_PATH_DELAY_ESTIMATOR_H_
 #define WEBRTC_MODULES_AUDIO_PROCESSING_AEC3_ECHO_PATH_DELAY_ESTIMATOR_H_
 
 #include <vector>
 
+#include "webrtc/api/optional.h"
 #include "webrtc/modules/audio_processing/aec3/decimator_by_4.h"
 #include "webrtc/modules/audio_processing/aec3/downsampled_render_buffer.h"
 #include "webrtc/modules/audio_processing/aec3/matched_filter.h"
 #include "webrtc/modules/audio_processing/aec3/matched_filter_lag_aggregator.h"
 #include "webrtc/modules/audio_processing/include/audio_processing.h"
 #include "webrtc/rtc_base/constructormagic.h"
-#include "webrtc/rtc_base/optional.h"
 
 namespace webrtc {
 
 class ApmDataDumper;
 
 // Estimates the delay of the echo path.
 class EchoPathDelayEstimator {
  public:
   EchoPathDelayEstimator(ApmDataDumper* data_dumper,
                          const AudioProcessing::Config::EchoCanceller3& config);
@@ skipping 11 matching lines @@
   ApmDataDumper* const data_dumper_;
   DecimatorBy4 capture_decimator_;
   MatchedFilter matched_filter_;
   MatchedFilterLagAggregator matched_filter_lag_aggregator_;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(EchoPathDelayEstimator);
 };
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_AUDIO_PROCESSING_AEC3_ECHO_PATH_DELAY_ESTIMATOR_H_