Replace const -> constexpr for rtcp Packet Type
for consistency with other rtcp packet classes.

BUG=webrtc:5260

Review-Url: https://codereview.webrtc.org/2361853002
Cr-Commit-Position: refs/heads/master@{#14648}
diff --git a/webrtc/modules/rtp_rtcp/source/rtcp_packet/bye.cc b/webrtc/modules/rtp_rtcp/source/rtcp_packet/bye.cc
index 610dfe3..cdb45b0 100644
--- a/webrtc/modules/rtp_rtcp/source/rtcp_packet/bye.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtcp_packet/bye.cc
@@ -19,7 +19,7 @@
 
 namespace webrtc {
 namespace rtcp {
-
+constexpr uint8_t Bye::kPacketType;
 // Bye packet (BYE) (RFC 3550).
 //
 //        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
@@ -35,7 +35,7 @@
 Bye::Bye() : sender_ssrc_(0) {}
 
 bool Bye::Parse(const CommonHeader& packet) {
-  RTC_DCHECK(packet.type() == kPacketType);
+  RTC_DCHECK_EQ(packet.type(), kPacketType);
 
   const uint8_t src_count = packet.count();
   // Validate packet.
diff --git a/webrtc/modules/rtp_rtcp/source/rtcp_packet/bye.h b/webrtc/modules/rtp_rtcp/source/rtcp_packet/bye.h
index c1db9e8..744423e 100644
--- a/webrtc/modules/rtp_rtcp/source/rtcp_packet/bye.h
+++ b/webrtc/modules/rtp_rtcp/source/rtcp_packet/bye.h
@@ -24,7 +24,7 @@
 
 class Bye : public RtcpPacket {
  public:
-  static const uint8_t kPacketType = 203;
+  static constexpr uint8_t kPacketType = 203;
 
   Bye();
   ~Bye() override {}
diff --git a/webrtc/modules/rtp_rtcp/source/rtcp_packet/pli.cc b/webrtc/modules/rtp_rtcp/source/rtcp_packet/pli.cc
index 7fdcc16..7838fcc 100644
--- a/webrtc/modules/rtp_rtcp/source/rtcp_packet/pli.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtcp_packet/pli.cc
@@ -16,7 +16,7 @@
 
 namespace webrtc {
 namespace rtcp {
-
+constexpr uint8_t Pli::kFeedbackMessageType;
 // RFC 4585: Feedback format.
 //
 // Common packet format:
@@ -37,8 +37,8 @@
 // Picture loss indication (PLI) (RFC 4585).
 // FCI: no feedback control information.
 bool Pli::Parse(const CommonHeader& packet) {
-  RTC_DCHECK(packet.type() == kPacketType);
-  RTC_DCHECK(packet.fmt() == kFeedbackMessageType);
+  RTC_DCHECK_EQ(packet.type(), kPacketType);
+  RTC_DCHECK_EQ(packet.fmt(), kFeedbackMessageType);
 
   if (packet.payload_size_bytes() < kCommonFeedbackLength) {
     LOG(LS_WARNING) << "Packet is too small to be a valid PLI packet";
diff --git a/webrtc/modules/rtp_rtcp/source/rtcp_packet/pli.h b/webrtc/modules/rtp_rtcp/source/rtcp_packet/pli.h
index 64caf1b..2ed6cd7 100644
--- a/webrtc/modules/rtp_rtcp/source/rtcp_packet/pli.h
+++ b/webrtc/modules/rtp_rtcp/source/rtcp_packet/pli.h
@@ -20,7 +20,7 @@
 // Picture loss indication (PLI) (RFC 4585).
 class Pli : public Psfb {
  public:
-  static const uint8_t kFeedbackMessageType = 1;
+  static constexpr uint8_t kFeedbackMessageType = 1;
 
   Pli() {}
   ~Pli() override {}
diff --git a/webrtc/modules/rtp_rtcp/source/rtcp_packet/receiver_report.cc b/webrtc/modules/rtp_rtcp/source/rtcp_packet/receiver_report.cc
index 808190a..93da4dc 100644
--- a/webrtc/modules/rtp_rtcp/source/rtcp_packet/receiver_report.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtcp_packet/receiver_report.cc
@@ -17,7 +17,7 @@
 
 namespace webrtc {
 namespace rtcp {
-//
+constexpr uint8_t ReceiverReport::kPacketType;
 // RTCP receiver report (RFC 3550).
 //
 //   0                   1                   2                   3
@@ -30,7 +30,7 @@
 //  |                         report block(s)                       |
 //  |                            ....                               |
 bool ReceiverReport::Parse(const CommonHeader& packet) {
-  RTC_DCHECK(packet.type() == kPacketType);
+  RTC_DCHECK_EQ(packet.type(), kPacketType);
 
   const uint8_t report_blocks_count = packet.count();
 
diff --git a/webrtc/modules/rtp_rtcp/source/rtcp_packet/receiver_report.h b/webrtc/modules/rtp_rtcp/source/rtcp_packet/receiver_report.h
index 2bfe174..c900d9c 100644
--- a/webrtc/modules/rtp_rtcp/source/rtcp_packet/receiver_report.h
+++ b/webrtc/modules/rtp_rtcp/source/rtcp_packet/receiver_report.h
@@ -24,9 +24,8 @@
 
 class ReceiverReport : public RtcpPacket {
  public:
-  static const uint8_t kPacketType = 201;
+  static constexpr uint8_t kPacketType = 201;
   ReceiverReport() : sender_ssrc_(0) {}
-
   ~ReceiverReport() override {}
 
   // Parse assumes header is already parsed and validated.
diff --git a/webrtc/modules/rtp_rtcp/source/rtcp_packet/sdes.cc b/webrtc/modules/rtp_rtcp/source/rtcp_packet/sdes.cc
index 9c44547..b0a5e78 100644
--- a/webrtc/modules/rtp_rtcp/source/rtcp_packet/sdes.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtcp_packet/sdes.cc
@@ -19,6 +19,7 @@
 
 namespace webrtc {
 namespace rtcp {
+constexpr uint8_t Sdes::kPacketType;
 // Source Description (SDES) (RFC 3550).
 //
 //         0                   1                   2                   3
@@ -62,7 +63,7 @@
 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
diff --git a/webrtc/modules/rtp_rtcp/source/rtcp_packet/sdes.h b/webrtc/modules/rtp_rtcp/source/rtcp_packet/sdes.h
index d9a9526..3e5abfe 100644
--- a/webrtc/modules/rtp_rtcp/source/rtcp_packet/sdes.h
+++ b/webrtc/modules/rtp_rtcp/source/rtcp_packet/sdes.h
@@ -28,7 +28,7 @@
     uint32_t ssrc;
     std::string cname;
   };
-  static const uint8_t kPacketType = 202;
+  static constexpr uint8_t kPacketType = 202;
 
   Sdes();
   ~Sdes() override;
diff --git a/webrtc/modules/rtp_rtcp/source/rtcp_packet/sender_report.cc b/webrtc/modules/rtp_rtcp/source/rtcp_packet/sender_report.cc
index 5e3a6cd..312b3f9 100644
--- a/webrtc/modules/rtp_rtcp/source/rtcp_packet/sender_report.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtcp_packet/sender_report.cc
@@ -17,6 +17,7 @@
 
 namespace webrtc {
 namespace rtcp {
+constexpr uint8_t SenderReport::kPacketType;
 //    Sender report (SR) (RFC 3550).
 //     0                   1                   2                   3
 //     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
@@ -43,7 +44,7 @@
       sender_octet_count_(0) {}
 
 bool SenderReport::Parse(const CommonHeader& packet) {
-  RTC_DCHECK(packet.type() == kPacketType);
+  RTC_DCHECK_EQ(packet.type(), kPacketType);
 
   const uint8_t report_block_count = packet.count();
   if (packet.payload_size_bytes() <
diff --git a/webrtc/modules/rtp_rtcp/source/rtcp_packet/sender_report.h b/webrtc/modules/rtp_rtcp/source/rtcp_packet/sender_report.h
index 91a66b7..4064595 100644
--- a/webrtc/modules/rtp_rtcp/source/rtcp_packet/sender_report.h
+++ b/webrtc/modules/rtp_rtcp/source/rtcp_packet/sender_report.h
@@ -24,7 +24,7 @@
 
 class SenderReport : public RtcpPacket {
  public:
-  static const uint8_t kPacketType = 200;
+  static constexpr uint8_t kPacketType = 200;
 
   SenderReport();
   ~SenderReport() override {}