Removes QUIC flag and code that shifts cubic epoch on quiescence, since it's buggy and should not b…

net/quic/core/congestion_control/cubic.cc

Index: net/quic/core/congestion_control/cubic.cc
diff --git a/net/quic/core/congestion_control/cubic.cc b/net/quic/core/congestion_control/cubic.cc
index 2690f188619ec2bbbba745d5ff7529c180a74289..fc596c973f924fa567dcf1d2f77fc033db0beb9e 100644
--- a/net/quic/core/congestion_control/cubic.cc
+++ b/net/quic/core/congestion_control/cubic.cc
@@ -81,18 +81,9 @@ void Cubic::Reset() {
 }
 
 void Cubic::OnApplicationLimited() {
-  if (FLAGS_shift_quic_cubic_epoch_when_app_limited) {
-    // When sender is not using the available congestion window, Cubic's epoch
-    // should not continue growing. Record the time when sender goes into an
-    // app-limited period here, to compensate later when cwnd growth happens.
-    if (app_limited_start_time_ == QuicTime::Zero()) {
-      app_limited_start_time_ = clock_->ApproximateNow();
-    }
-  } else {
-    // When sender is not using the available congestion window, Cubic's epoch
-    // should not continue growing. Reset the epoch when in such a period.
-    epoch_ = QuicTime::Zero();
-  }
+  // When sender is not using the available congestion window, Cubic's epoch
+  // should not continue growing. Reset the epoch when in such a period.
+  epoch_ = QuicTime::Zero();
 }
 
 QuicPacketCount Cubic::CongestionWindowAfterPacketLoss(
@@ -139,17 +130,6 @@ QuicPacketCount Cubic::CongestionWindowAfterAck(
                (last_max_congestion_window_ - current_congestion_window)));
       origin_point_congestion_window_ = last_max_congestion_window_;
     }
-  } else {
-    // If sender was app-limited, then freeze congestion window growth during
-    // app-limited period. Continue growth now by shifting the epoch-start
-    // through the app-limited period.
-    if (FLAGS_shift_quic_cubic_epoch_when_app_limited &&
-        app_limited_start_time_ != QuicTime::Zero()) {
-      QuicTime::Delta shift = current_time - app_limited_start_time_;
-      DVLOG(1) << "Shifting epoch for quiescence by " << shift.ToMicroseconds();
-      epoch_ = epoch_ + shift;
-      app_limited_start_time_ = QuicTime::Zero();
-    }
   }
 
   // Change the time unit from microseconds to 2^10 fractions per second. Take