Fixes bugs in packet size computation in the creator and in the framer

net/quic/quic_packet_creator.h

Index: net/quic/quic_packet_creator.h
diff --git a/net/quic/quic_packet_creator.h b/net/quic/quic_packet_creator.h
index 5eadff41020c46c3db235ba2f4c3d44d3f1e3cfc..83eda2309123e2fbab371a4c951d6b048ffab825 100644
--- a/net/quic/quic_packet_creator.h
+++ b/net/quic/quic_packet_creator.h
@@ -221,9 +221,10 @@ class NET_EXPORT_PRIVATE QuicPacketCreator : public QuicFecBuilderInterface {
 
   static bool ShouldRetransmit(const QuicFrame& frame);
 
-  // Starts a new FEC group with the next serialized packet, if FEC is enabled
-  // and there is not already an FEC group open.
-  InFecGroup MaybeStartFec();
+  // Updates sequence number length on a packet or FEC group boundary.
+  // Also starts an FEC group if FEC protection is on and there is not already
+  // an FEC group open.
+  InFecGroup MaybeUpdateLengthsAndStartFec();
 
   void FillPacketHeader(QuicFecGroupNumber fec_group,
                         bool fec_flag,