Replace const -> constexpr for rtcp Packet Type

webrtc/modules/rtp_rtcp/source/rtcp_packet/sender_report.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_SENDER_REPORT_H_
 #define WEBRTC_MODULES_RTP_RTCP_SOURCE_RTCP_PACKET_SENDER_REPORT_H_
 
 #include <vector>
 
 #include "webrtc/base/constructormagic.h"
 #include "webrtc/modules/rtp_rtcp/source/rtcp_packet.h"
 #include "webrtc/modules/rtp_rtcp/source/rtcp_packet/report_block.h"
 #include "webrtc/system_wrappers/include/ntp_time.h"
 
 namespace webrtc {
 namespace rtcp {
 class CommonHeader;
 
 class SenderReport : public RtcpPacket {
  public:
-  static const uint8_t kPacketType = 200;
+  static constexpr uint8_t kPacketType = 200;
 
   SenderReport();
   ~SenderReport() override {}
 
   // Parse assumes header is already parsed and validated.
   bool Parse(const CommonHeader& packet);
 
   void From(uint32_t ssrc) { sender_ssrc_ = ssrc; }
   void WithNtp(NtpTime ntp) { ntp_ = ntp; }
   void WithRtpTimestamp(uint32_t rtp_timestamp) {
@@ skipping 39 matching lines @@
   uint32_t sender_packet_count_;
   uint32_t sender_octet_count_;
   std::vector<ReportBlock> report_blocks_;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(SenderReport);
 };
 
 }  // namespace rtcp
 }  // namespace webrtc
 #endif  // WEBRTC_MODULES_RTP_RTCP_SOURCE_RTCP_PACKET_SENDER_REPORT_H_