Remove the no longer used kPACE connection option. No functional change.

net/quic/crypto/crypto_protocol.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NET_QUIC_CRYPTO_CRYPTO_PROTOCOL_H_
 #define NET_QUIC_CRYPTO_CRYPTO_PROTOCOL_H_
 
 #include <string>
 
 #include "net/base/net_export.h"
@@ skipping 39 matching lines @@
 const QuicTag kSRBF = TAG('S', 'R', 'B', 'F');   // Socket receive buffer
 
 // Congestion control feedback types
 const QuicTag kQBIC = TAG('Q', 'B', 'I', 'C');   // TCP cubic
 
 // Connection options (COPT) values
 const QuicTag kTBBR = TAG('T', 'B', 'B', 'R');   // Reduced Buffer Bloat TCP
 const QuicTag kRENO = TAG('R', 'E', 'N', 'O');   // Reno Congestion Control
 const QuicTag kBYTE = TAG('B', 'Y', 'T', 'E');   // TCP cubic or reno in bytes
 const QuicTag kIW10 = TAG('I', 'W', '1', '0');   // Force ICWND to 10
-const QuicTag kPACE = TAG('P', 'A', 'C', 'E');   // Enable pacing
 const QuicTag k1CON = TAG('1', 'C', 'O', 'N');   // Emulate a single connection
 const QuicTag kNTLP = TAG('N', 'T', 'L', 'P');   // No tail loss probe
 const QuicTag kNCON = TAG('N', 'C', 'O', 'N');   // N Connection Congestion Ctrl
 const QuicTag kNRTO = TAG('N', 'R', 'T', 'O');   // CWND reduction on loss
 const QuicTag kTIME = TAG('T', 'I', 'M', 'E');   // Time based loss detection
 const QuicTag kMIN1 = TAG('M', 'I', 'N', '1');   // Min CWND of 1 packet
 const QuicTag kMIN4 = TAG('M', 'I', 'N', '4');   // Min CWND of 4 packets,
                                                  // with a min rate of 1 BDP.
 
 // Optional support of truncated Connection IDs.  If sent by a peer, the value
@@ skipping 106 matching lines @@
 // amplification factor of any mirror DoS attack.
 //
 // A client may pad an inchoate client hello to a size larger than
 // kClientHelloMinimumSize to make it more likely to receive a complete
 // rejection message.
 const size_t kClientHelloMinimumSize = 1024;
 
 }  // namespace net
 
 #endif  // NET_QUIC_CRYPTO_CRYPTO_PROTOCOL_H_