Replace const -> constexpr for rtcp Packet Type

webrtc/modules/rtp_rtcp/source/rtcp_packet/sdes.cc

Index: webrtc/modules/rtp_rtcp/source/rtcp_packet/sdes.cc
diff --git a/webrtc/modules/rtp_rtcp/source/rtcp_packet/sdes.cc b/webrtc/modules/rtp_rtcp/source/rtcp_packet/sdes.cc
index 3a905ba3157e8e90880fad1e621ea1772942e704..a86e69c7441e8939af12ba906d7190605dfff52f 100644
--- a/webrtc/modules/rtp_rtcp/source/rtcp_packet/sdes.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtcp_packet/sdes.cc
@@ -10,6 +10,8 @@
 
 #include "webrtc/modules/rtp_rtcp/source/rtcp_packet/sdes.h"
 
+#include <utility>
+
 #include "webrtc/base/checks.h"
 #include "webrtc/base/logging.h"
 #include "webrtc/modules/rtp_rtcp/source/byte_io.h"
@@ -17,6 +19,7 @@
 
 namespace webrtc {
 namespace rtcp {
+constexpr uint8_t Sdes::kPacketType;
 // Source Description (SDES) (RFC 3550).
 //
 //         0                   1                   2                   3
@@ -60,7 +63,7 @@ Sdes::Sdes() : block_length_(RtcpPacket::kHeaderLength) {}
 Sdes::~Sdes() {}
 
 bool Sdes::Parse(const CommonHeader& packet) {
-  RTC_DCHECK(packet.type() == kPacketType);
+  RTC_DCHECK_EQ(packet.type(), kPacketType);
 
   uint8_t number_of_chunks = packet.count();
   std::vector<Chunk> chunks;  // Read chunk into temporary array, so that in