relnote: Deprecate FLAGS_quic_allow_ip_migration.

net/quic/quic_connection.cc

Index: net/quic/quic_connection.cc
diff --git a/net/quic/quic_connection.cc b/net/quic/quic_connection.cc
index 682a0a556d35b1a296def180be80da4b9156fb51..1bfc6ff5211c823369c8120d1d0449a75196f889 100644
--- a/net/quic/quic_connection.cc
+++ b/net/quic/quic_connection.cc
@@ -1457,11 +1457,9 @@ void QuicConnection::WriteIfNotBlocked() {
 }
 
 bool QuicConnection::ProcessValidatedPacket() {
-  if ((peer_ip_changed_ && !FLAGS_quic_allow_ip_migration) ||
-      self_ip_changed_ || self_port_changed_) {
-    SendConnectionCloseWithDetails(
-        QUIC_ERROR_MIGRATING_ADDRESS,
-        "Neither IP address migration, nor self port migration are supported.");
+  if (self_ip_changed_ || self_port_changed_) {
+    SendConnectionCloseWithDetails(QUIC_ERROR_MIGRATING_ADDRESS,
+                                   "Self address migration is not supported.");
     return false;
   }