Fix version manager that flip flag in-flight does not make supported versions change.

net/tools/quic/quic_dispatcher.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/tools/quic/quic_dispatcher.h"
 
 #include <utility>
 
 #include "base/debug/stack_trace.h"
 #include "base/logging.h"
@@ skipping 293 matching lines @@
     return HandlePacketForTimeWait(header);
   }
 
   // The packet has an unknown connection ID.
 
   // Unless the packet provides a version, assume that we can continue
   // processing using our preferred version.
   QuicVersion version = GetSupportedVersions().front();
   if (header.version_flag) {
     QuicVersion packet_version = header.versions.front();
+    if (FLAGS_quic_fix_version_manager &&
+        framer_.supported_versions() != GetSupportedVersions()) {
+      // Reset framer's version if version flags change in flight.
+      framer_.SetSupportedVersions(GetSupportedVersions());
+    }
     if (!framer_.IsSupportedVersion(packet_version)) {
       if (ShouldCreateSessionForUnknownVersion(framer_.last_version_tag())) {
         return true;
       }
       // Since the version is not supported, send a version negotiation
       // packet and stop processing the current packet.
       time_wait_list_manager()->SendVersionNegotiationPacket(
           connection_id, GetSupportedVersions(), current_server_address_,
           current_client_address_);
       return false;
@@ skipping 663 matching lines @@
 void QuicDispatcher::DeliverPacketsToSession(
     const std::list<BufferedPacket>& packets,
     QuicSession* session) {
   for (const BufferedPacket& packet : packets) {
     session->ProcessUdpPacket(packet.server_address, packet.client_address,
                               *(packet.packet));
   }
 }
 
 }  // namespace net