relnote: Avoid redundant recvmmsg when the previous recvmmsg returned

net/quic/quic_flags.cc

Index: net/quic/quic_flags.cc
diff --git a/net/quic/quic_flags.cc b/net/quic/quic_flags.cc
index 8c7dc0d6c60a0e81a1e21f1db35841a7a7543afc..3feb64664fdfdb9202b61315719b89e5f1d8bcc1 100644
--- a/net/quic/quic_flags.cc
+++ b/net/quic/quic_flags.cc
@@ -80,3 +80,8 @@ bool FLAGS_shift_quic_cubic_epoch_when_app_limited = true;
 // If true, accounts for available (implicitly opened) streams under a separate
 // quota from open streams, which is 10 times larger.
 bool FLAGS_allow_many_available_streams = true;
+
+// If true, QuicPacketReader::ReadAndDispatchPackets will only return true if
+// recvmmsg fills all of the passed in messages. Otherwise, it will return true
+// if recvmmsg read any messages.
+bool FLAGS_quic_read_packets_full_recvmmsg = true;