Don't let PRR kick in if there is less than a packets worth of bytes in

net/quic/congestion_control/tcp_cubic_sender.cc

Index: net/quic/congestion_control/tcp_cubic_sender.cc
diff --git a/net/quic/congestion_control/tcp_cubic_sender.cc b/net/quic/congestion_control/tcp_cubic_sender.cc
index a4b42b4cc1b3f9696f0ead1b3458b60d088e5677..3e7115d3a8a32b0d59842c5d24be46a2c29412f5 100644
--- a/net/quic/congestion_control/tcp_cubic_sender.cc
+++ b/net/quic/congestion_control/tcp_cubic_sender.cc
@@ -332,7 +332,7 @@ QuicTime::Delta TcpCubicSender::PrrTimeUntilSend(
     QuicByteCount bytes_in_flight) const {
   DCHECK(InRecovery());
   // Return QuicTime::Zero In order to ensure limited transmit always works.
-  if (prr_out_ == 0) {
+  if (prr_out_ == 0 || bytes_in_flight < kMaxSegmentSize) {
     return QuicTime::Delta::Zero();
   }
   if (SendWindow() > bytes_in_flight) {