Refactor to create a new LossDetectionInterface used by the

net/quic/quic_sent_packet_manager_test.cc

Index: net/quic/quic_sent_packet_manager_test.cc
diff --git a/net/quic/quic_sent_packet_manager_test.cc b/net/quic/quic_sent_packet_manager_test.cc
index 5adff71297ce21a8cff3a8cfd5f1a6115cceb428..c8926fbe0179c25207167492df1c1b6a5f4d2689 100644
--- a/net/quic/quic_sent_packet_manager_test.cc
+++ b/net/quic/quic_sent_packet_manager_test.cc
@@ -35,6 +35,12 @@ class QuicSentPacketManagerTest : public ::testing::TestWithParam<bool> {
     STLDeleteElements(&packets_);
   }
 
+  virtual void SetUp() {
+    // Ack handling requests a smoothed rtt for loss detection.
+    EXPECT_CALL(*send_algorithm_, SmoothedRtt())
+        .WillRepeatedly(Return(QuicTime::Delta::FromMilliseconds(1)));
+  }
+
   void VerifyUnackedPackets(QuicPacketSequenceNumber* packets,
                             size_t num_packets) {
     if (num_packets == 0) {