Add relevant tags for PCC Congestion control

net/quic/core/crypto/crypto_protocol.h

Index: net/quic/core/crypto/crypto_protocol.h
diff --git a/net/quic/core/crypto/crypto_protocol.h b/net/quic/core/crypto/crypto_protocol.h
index eef32f283652f44ec624a16bf2bd6f90bc414db6..d073226c7280c1a8dbe6a08980d4865aaed20f21 100644
--- a/net/quic/core/crypto/crypto_protocol.h
+++ b/net/quic/core/crypto/crypto_protocol.h
@@ -82,6 +82,8 @@ const QuicTag kTBBR = TAG('T', 'B', 'B', 'R');   // Reduced Buffer Bloat TCP
 const QuicTag k1RTT = TAG('1', 'R', 'T', 'T');   // STARTUP in BBR for 1 RTT
 const QuicTag k2RTT = TAG('2', 'R', 'T', 'T');   // STARTUP in BBR for 2 RTTs
 const QuicTag kRENO = TAG('R', 'E', 'N', 'O');   // Reno Congestion Control
+const QuicTag kTPCC = TAG('P', 'C', 'C', '\0');  // Performance-Oriented
+                                                 // Congestion Control
 const QuicTag kBYTE = TAG('B', 'Y', 'T', 'E');   // TCP cubic or reno in bytes
 const QuicTag kRATE = TAG('R', 'A', 'T', 'E');   // TCP cubic rate based sending
 const QuicTag kIW03 = TAG('I', 'W', '0', '3');   // Force ICWND to 3