relnote: Protect against a QUIC crash bug but logging a DFATAL and

net/quic/quic_packet_generator.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_packet_generator.h"
 
 #include "base/basictypes.h"
 #include "base/logging.h"
 #include "net/quic/quic_ack_notifier.h"
 #include "net/quic/quic_fec_group.h"
@@ skipping 439 matching lines @@
   if (success && debug_delegate_) {
     debug_delegate_->OnFrameAddedToPacket(frame);
   }
   return success;
 }
 
 void QuicPacketGenerator::SerializeAndSendPacket() {
   char buffer[kMaxPacketSize];
   SerializedPacket serialized_packet =
       packet_creator_.SerializePacket(buffer, kMaxPacketSize);
-  DCHECK(serialized_packet.packet);
+  if (serialized_packet.packet == nullptr) {
+    LOG(DFATAL) << "Failed to SerializePacket. fec_policy:" << fec_send_policy_
+                << " should_fec_protect_:" << should_fec_protect_;
+    delegate_->CloseConnection(QUIC_FAILED_TO_SERIALIZE_PACKET, false);
+    return;
+  }
 
   // There may be AckNotifiers interested in this packet.
   serialized_packet.notifiers.swap(ack_notifiers_);
   ack_notifiers_.clear();
 
   delegate_->OnSerializedPacket(serialized_packet);
   MaybeSendFecPacketAndCloseGroup(/*force=*/false, /*is_fec_timeout=*/false);
 
   // Maximum packet size may be only enacted while no packet is currently being
   // constructed, so here we have a good opportunity to actually change it.
@@ skipping 74 matching lines @@
 void QuicPacketGenerator::set_encryption_level(EncryptionLevel level) {
   packet_creator_.set_encryption_level(level);
 }
 
 void QuicPacketGenerator::SetEncrypter(EncryptionLevel level,
                                        QuicEncrypter* encrypter) {
   packet_creator_.SetEncrypter(level, encrypter);
 }
 
 }  // namespace net