Deprecate FLAGS_quic_read_packets_full_recvmmsg.

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 67519c0c34dd870547436b2afd1ca21f98f0a341..5ecec05ad245f1ee83455c186e0b40b893292985 100644
--- a/net/quic/quic_flags.cc
+++ b/net/quic/quic_flags.cc
@@ -69,11 +69,6 @@ bool FLAGS_shift_quic_cubic_epoch_when_app_limited = true;
 // 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;
-
 // If true, QUIC will measure head of line (HOL) blocking due between
 // streams due to packet losses on the headers stream.  The
 // measurements will be surfaced via UMA histogram