Remove QUIC_VERSION_15 now that Chrome Stable supports QUIC_VERSION_16.

net/quic/test_tools/quic_test_utils.cc

Index: net/quic/test_tools/quic_test_utils.cc
diff --git a/net/quic/test_tools/quic_test_utils.cc b/net/quic/test_tools/quic_test_utils.cc
index 9b54f94030af0d0365bccee4af8f661ee77e6671..0fbac6aeec0a69ae8806f436a551a9af321689d2 100644
--- a/net/quic/test_tools/quic_test_utils.cc
+++ b/net/quic/test_tools/quic_test_utils.cc
@@ -43,20 +43,16 @@ class TestAlarm : public QuicAlarm {
 
 }  // namespace
 
-QuicAckFrame MakeAckFrame(QuicPacketSequenceNumber largest_observed,
-                          QuicPacketSequenceNumber least_unacked) {
+QuicAckFrame MakeAckFrame(QuicPacketSequenceNumber largest_observed) {
   QuicAckFrame ack;
   ack.received_info.largest_observed = largest_observed;
   ack.received_info.entropy_hash = 0;
-  ack.sent_info.least_unacked = least_unacked;
-  ack.sent_info.entropy_hash = 0;
   return ack;
 }
 
 QuicAckFrame MakeAckFrameWithNackRanges(
     size_t num_nack_ranges, QuicPacketSequenceNumber least_unacked) {
-  QuicAckFrame ack = MakeAckFrame(2 * num_nack_ranges + least_unacked,
-                                  least_unacked);
+  QuicAckFrame ack = MakeAckFrame(2 * num_nack_ranges + least_unacked);
   // Add enough missing packets to get num_nack_ranges nack ranges.
   for (QuicPacketSequenceNumber i = 1; i < 2 * num_nack_ranges; i += 2) {
     ack.received_info.missing_packets.insert(least_unacked + i);