Connect up IETF QUIC Max ACK Delay transport parameter

This CL sets the QuicSentPacketManager's ACK Delay from the
MAX ACK Delay transport parameter.

gfe-relnote: N/A done only if IETF QUIC enabled & negotiated.
PiperOrigin-RevId: 260502360
Change-Id: Idd8a9d0fe36e7ab0794aa7532d608489866248eb

quic/core/crypto/crypto_handshake_message.cc

diff --git a/quic/core/crypto/crypto_handshake_message.cc b/quic/core/crypto/crypto_handshake_message.cc
index bf1df2b..022a86b 100644
--- a/quic/core/crypto/crypto_handshake_message.cc
+++ b/quic/core/crypto/crypto_handshake_message.cc
@@ -278,6 +278,7 @@
       case kMIBS:
       case kSCLS:
       case kTCID:
+      case kMAD:
         // uint32_t value
         if (it->second.size() == 4) {
           uint32_t value;

quic/core/crypto/crypto_protocol.h

diff --git a/quic/core/crypto/crypto_protocol.h b/quic/core/crypto/crypto_protocol.h
index f2033e1..fdd4fd1 100644
--- a/quic/core/crypto/crypto_protocol.h
+++ b/quic/core/crypto/crypto_protocol.h
@@ -238,6 +238,8 @@
 const QuicTag kUAID = TAG('U', 'A', 'I', 'D');   // Client's User Agent ID.
 const QuicTag kXLCT = TAG('X', 'L', 'C', 'T');   // Expected leaf certificate.
 
+const QuicTag kMAD  = TAG('M', 'A', 'D', 0);     // Max Ack Delay (IETF QUIC)
+
 // Rejection tags
 const QuicTag kRREJ = TAG('R', 'R', 'E', 'J');   // Reasons for server sending