Land recent QUIC changes.

net/quic/congestion_control/cubic.cc

Index: net/quic/congestion_control/cubic.cc
diff --git a/net/quic/congestion_control/cubic.cc b/net/quic/congestion_control/cubic.cc
index c1faeb37c7ce2f31aef753b0c16ec111c9e86d9d..1c415002f94837f8e3ad17285d5c18b25b60d24d 100644
--- a/net/quic/congestion_control/cubic.cc
+++ b/net/quic/congestion_control/cubic.cc
@@ -134,12 +134,11 @@ QuicTcpCongestionWindow Cubic::CongestionWindowAfterAck(
     QuicTcpCongestionWindow current_congestion_window,
     QuicTime::Delta delay_min) {
   acked_packets_count_ += 1;  // Packets acked.
-  QuicTime current_time = clock_->Now();
+  QuicTime current_time = clock_->ApproximateNow();
 
   // Cubic is "independent" of RTT, the update is limited by the time elapsed.
   if (last_congestion_window_ == current_congestion_window &&
       (current_time.Subtract(last_update_time_) <= MaxCubicTimeInterval())) {
-    DCHECK(epoch_.IsInitialized());
     return std::max(last_target_congestion_window_,
                     estimated_tcp_congestion_window_);
   }