Move optional.h to webrtc/api/

webrtc/modules/audio_processing/aec3/matched_filter.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_H_
 #define WEBRTC_MODULES_AUDIO_PROCESSING_AEC3_MATCHED_FILTER_H_
 
 #include <array>
 #include <memory>
 #include <vector>
 
+#include "webrtc/api/optional.h"
 #include "webrtc/modules/audio_processing/aec3/aec3_common.h"
 #include "webrtc/modules/audio_processing/aec3/downsampled_render_buffer.h"
 #include "webrtc/rtc_base/constructormagic.h"
-#include "webrtc/rtc_base/optional.h"
 
 namespace webrtc {
 namespace aec3 {
 
 #if defined(WEBRTC_HAS_NEON)
 
 // Filter core for the matched filter that is optimized for NEON.
 void MatchedFilterCore_NEON(size_t x_start_index,
                             float x2_sum_threshold,
                             rtc::ArrayView<const float> x,
@@ skipping 78 matching lines @@
   std::vector<std::vector<float>> filters_;
   std::vector<LagEstimate> lag_estimates_;
   const float excitation_limit_;
 
   RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(MatchedFilter);
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_AUDIO_PROCESSING_AEC3_MATCHED_FILTER_H_