Update from chromium https://crrev.com/302282

net/quic/quic_framer.cc

 // 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.
 
 #include "net/quic/quic_framer.h"
 
 #include "base/containers/hash_tables.h"
 #include "base/stl_util.h"
 #include "net/quic/crypto/crypto_framer.h"
 #include "net/quic/crypto/crypto_handshake_message.h"
@@ skipping 865 matching lines @@
       public_header->connection_id_length = PACKET_8BYTE_CONNECTION_ID;
       break;
     case PACKET_PUBLIC_FLAGS_4BYTE_CONNECTION_ID:
       // If the connection_id is truncated, expect to read the last serialized
       // connection_id.
       if (!reader_->ReadBytes(&public_header->connection_id,
                               PACKET_4BYTE_CONNECTION_ID)) {
         set_detailed_error("Unable to read ConnectionId.");
         return false;
       }
-      if ((public_header->connection_id & k4ByteConnectionIdMask) !=
+      if (last_serialized_connection_id_ &&
+          (public_header->connection_id & k4ByteConnectionIdMask) !=
           (last_serialized_connection_id_ & k4ByteConnectionIdMask)) {
         set_detailed_error("Truncated 4 byte ConnectionId does not match "
                            "previous connection_id.");
         return false;
       }
       public_header->connection_id_length = PACKET_4BYTE_CONNECTION_ID;
       public_header->connection_id = last_serialized_connection_id_;
       break;
     case PACKET_PUBLIC_FLAGS_1BYTE_CONNECTION_ID:
       if (!reader_->ReadBytes(&public_header->connection_id,
                               PACKET_1BYTE_CONNECTION_ID)) {
         set_detailed_error("Unable to read ConnectionId.");
         return false;
       }
-      if ((public_header->connection_id & k1ByteConnectionIdMask) !=
+      if (last_serialized_connection_id_ &&
+          (public_header->connection_id & k1ByteConnectionIdMask) !=
           (last_serialized_connection_id_ & k1ByteConnectionIdMask)) {
         set_detailed_error("Truncated 1 byte ConnectionId does not match "
                            "previous connection_id.");
         return false;
       }
       public_header->connection_id_length = PACKET_1BYTE_CONNECTION_ID;
       public_header->connection_id = last_serialized_connection_id_;
       break;
     case PACKET_PUBLIC_FLAGS_0BYTE_CONNECTION_ID:
       public_header->connection_id_length = PACKET_0BYTE_CONNECTION_ID;
@@ skipping 1401 matching lines @@
 
 bool QuicFramer::RaiseError(QuicErrorCode error) {
   DVLOG(1) << "Error detail: " << detailed_error_;
   set_error(error);
   visitor_->OnError(this);
   reader_.reset(nullptr);
   return false;
 }
 
 }  // namespace net