Update QuicSentPacketManager to sample a new recent min rtt within the

net/quic/quic_sent_packet_manager.cc

Index: net/quic/quic_sent_packet_manager.cc
diff --git a/net/quic/quic_sent_packet_manager.cc b/net/quic/quic_sent_packet_manager.cc
index ba581672f17d8ba1c745af3cb103f3276b618056..d92140ad896468c667f54babcb60935482bff69b 100644
--- a/net/quic/quic_sent_packet_manager.cc
+++ b/net/quic/quic_sent_packet_manager.cc
@@ -38,6 +38,9 @@ static const size_t kMinHandshakeTimeoutMs = 10;
 static const size_t kDefaultMaxTailLossProbes = 2;
 static const int64 kMinTailLossProbeTimeoutMs = 10;
 
+// Number of samples before we force a new recent min rtt to be captured.
+static const size_t kNumMinRttSamplesAfterQuiescence = 2;
+
 bool HasCryptoHandshake(const TransmissionInfo& transmission_info) {
   if (transmission_info.retransmittable_frames == NULL) {
     return false;
@@ -444,6 +447,14 @@ bool QuicSentPacketManager::OnPacketSent(
     return false;
   }
 
+  if (unacked_packets_.bytes_in_flight() == 0) {
+    // TODO(ianswett): Consider being less aggressive to force a new
+    // recent_min_rtt, likely by not discarding a relatively new sample.
+    DVLOG(1) << "Sampling a new recent min rtt within 2 samples. currently:"
+             << rtt_stats_.recent_min_rtt().ToMilliseconds() << "ms";
+    rtt_stats_.SampleNewRecentMinRtt(kNumMinRttSamplesAfterQuiescence);
+  }
+
   // Only track packets as pending that the send algorithm wants us to track.
   const bool pending =
       send_algorithm_->OnPacketSent(sent_time,