Move optional.h to webrtc/api/

webrtc/modules/rtp_rtcp/source/rtcp_packet/extended_reports.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_MODULES_RTP_RTCP_SOURCE_RTCP_PACKET_EXTENDED_REPORTS_H_
 #define WEBRTC_MODULES_RTP_RTCP_SOURCE_RTCP_PACKET_EXTENDED_REPORTS_H_
 
 #include <vector>
 
+#include "webrtc/api/optional.h"
 #include "webrtc/modules/rtp_rtcp/source/rtcp_packet.h"
 #include "webrtc/modules/rtp_rtcp/source/rtcp_packet/dlrr.h"
 #include "webrtc/modules/rtp_rtcp/source/rtcp_packet/rrtr.h"
 #include "webrtc/modules/rtp_rtcp/source/rtcp_packet/target_bitrate.h"
 #include "webrtc/modules/rtp_rtcp/source/rtcp_packet/voip_metric.h"
-#include "webrtc/rtc_base/optional.h"
 
 namespace webrtc {
 namespace rtcp {
 class CommonHeader;
 
 // From RFC 3611: RTP Control Protocol Extended Reports (RTCP XR).
 class ExtendedReports : public RtcpPacket {
  public:
   static constexpr uint8_t kPacketType = 207;
 
@@ skipping 44 matching lines @@
 
   uint32_t sender_ssrc_;
   rtc::Optional<Rrtr> rrtr_block_;
   Dlrr dlrr_block_;  // Dlrr without items treated same as no dlrr block.
   rtc::Optional<VoipMetric> voip_metric_block_;
   rtc::Optional<TargetBitrate> target_bitrate_;
 };
 }  // namespace rtcp
 }  // namespace webrtc
 #endif  // WEBRTC_MODULES_RTP_RTCP_SOURCE_RTCP_PACKET_EXTENDED_REPORTS_H_