Stub for BBRv2, based on TCP congestion feedback frames.

net/quic/congestion_control/send_algorithm_interface.h

Index: net/quic/congestion_control/send_algorithm_interface.h
diff --git a/net/quic/congestion_control/send_algorithm_interface.h b/net/quic/congestion_control/send_algorithm_interface.h
index 8412a043856205660d2ae815e9b96fd9bd2497fa..12cf8f691ef8738ebbc7f46388be91e4361cf61f 100644
--- a/net/quic/congestion_control/send_algorithm_interface.h
+++ b/net/quic/congestion_control/send_algorithm_interface.h
@@ -51,10 +51,11 @@ class NET_EXPORT_PRIVATE SendAlgorithmInterface {
                                  const CongestionMap& acked_packets,
                                  const CongestionMap& lost_packets) = 0;
 
-  // Inform that we sent x bytes to the wire, and if that was a retransmission.
-  // Returns true if the packet should be tracked by the congestion manager,
-  // false otherwise. This is used by implementations such as tcp_cubic_sender
-  // that do not count outgoing ACK packets against the congestion window.
+  // Inform that we sent |bytes| to the wire, and if the packet is
+  // retransmittable. Returns true if the packet should be tracked by the
+  // congestion manager and included in bytes_in_flight, false otherwise.
+  // |bytes_in_flight| is the number of bytes in flight before the packet was
+  // sent.
   // Note: this function must be called for every packet sent to the wire.
   virtual bool OnPacketSent(QuicTime sent_time,
                             QuicByteCount bytes_in_flight,