gfe-relnote: (n/a) Remove unused QUIC connection option "BBQ4". Not protected.

Also changed kDerivedHighCWNDGain to 2.0f and fixed test 'DerivedCWNDGainStartup'.

PiperOrigin-RevId: 247060931
Change-Id: Ie1253736d8bc4dd81ba700ef0ee7826bba5eeb69

quic/core/congestion_control/bbr_sender.h

diff --git a/quic/core/congestion_control/bbr_sender.h b/quic/core/congestion_control/bbr_sender.h
index d01dbfe..843764b 100644
--- a/quic/core/congestion_control/bbr_sender.h
+++ b/quic/core/congestion_control/bbr_sender.h
@@ -164,6 +164,10 @@
     drain_gain_ = drain_gain;
   }
 
+  // Returns the current estimate of the RTT of the connection.  Outside of the
+  // edge cases, this is minimum RTT.
+  QuicTime::Delta GetMinRtt() const;
+
   DebugState ExportDebugState() const;
 
  private:
@@ -179,9 +183,6 @@
                          QuicRoundTripCount>
       MaxAckHeightFilter;
 
-  // Returns the current estimate of the RTT of the connection.  Outside of the
-  // edge cases, this is minimum RTT.
-  QuicTime::Delta GetMinRtt() const;
   // Returns whether the connection has achieved full bandwidth required to exit
   // the slow start.
   bool IsAtFullBandwidth() const;