Minor cleanup of QuicUnackedPacketMap to simplify the implementation of

net/quic/test_tools/quic_sent_packet_manager_peer.cc

Index: net/quic/test_tools/quic_sent_packet_manager_peer.cc
diff --git a/net/quic/test_tools/quic_sent_packet_manager_peer.cc b/net/quic/test_tools/quic_sent_packet_manager_peer.cc
index 7f7261596b3d3aeba28ae0e74e97051b6d22346c..db1a26d37bf93171f00236fededec73c50edba95 100644
--- a/net/quic/test_tools/quic_sent_packet_manager_peer.cc
+++ b/net/quic/test_tools/quic_sent_packet_manager_peer.cc
@@ -109,7 +109,15 @@ bool QuicSentPacketManagerPeer::HasUnackedCryptoPackets(
 // static
 size_t QuicSentPacketManagerPeer::GetNumRetransmittablePackets(
     const QuicSentPacketManager* sent_packet_manager) {
-  return sent_packet_manager->unacked_packets_.GetNumRetransmittablePackets();
+  size_t num_unacked_packets = 0;
+  for (QuicUnackedPacketMap::const_iterator it =
+           sent_packet_manager->unacked_packets_.begin();
+       it != sent_packet_manager->unacked_packets_.end(); ++it) {
+    if (it->second.retransmittable_frames != NULL) {
+      ++num_unacked_packets;
+    }
+  }
+  return num_unacked_packets;
 }
 
 // static