Discard old packets from the QuicSentPacketManager which are only

net/quic/quic_unacked_packet_map_test.cc

Index: net/quic/quic_unacked_packet_map_test.cc
diff --git a/net/quic/quic_unacked_packet_map_test.cc b/net/quic/quic_unacked_packet_map_test.cc
index 0a7bb2b490ea43801f7997e3fe187050becbbf5f..9c4a6a32888dc547dd12a448d4d21943b102cb58 100644
--- a/net/quic/quic_unacked_packet_map_test.cc
+++ b/net/quic/quic_unacked_packet_map_test.cc
@@ -7,6 +7,8 @@
 #include "net/quic/test_tools/quic_test_utils.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
+using std::min;
+
 namespace net {
 namespace test {
 namespace {
@@ -113,6 +115,18 @@ TEST_F(QuicUnackedPacketMapTest, RttOnly) {
   VerifyRetransmittablePackets(NULL, 0);
 }
 
+TEST_F(QuicUnackedPacketMapTest, DiscardOldRttOnly) {
+  // Acks are only tracked for RTT measurement purposes, and are discarded
+  // when more than 200 accumulate.
+  for (int i = 1; i < 400; ++i) {
+    unacked_packets_.AddPacket(CreateNonRetransmittablePacket(i));
+    unacked_packets_.SetSent(i, now_, kDefaultAckLength, false);
+    unacked_packets_.RemoveObsoletePackets();
+    EXPECT_EQ(static_cast<size_t>(min(i, 200)),
+              unacked_packets_.GetNumUnackedPacketsDebugOnly());
+  }
+}
+
 TEST_F(QuicUnackedPacketMapTest, RetransmittableInflightAndRtt) {
   // Simulate a retransmittable packet being sent and acked.
   unacked_packets_.AddPacket(CreateRetransmittablePacket(1));