Land recent QUIC changes.

net/quic/congestion_control/cubic.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/quic/congestion_control/cubic.h"
 
 #include "base/basictypes.h"
 #include "base/logging.h"
 #include "base/time.h"
 
@@ skipping 116 matching lines @@
     last_max_congestion_window_ = current_congestion_window;
   }
   epoch_ = QuicTime::Zero();  // Reset time.
   return (current_congestion_window * kBeta) >> 10;
 }
 
 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_);
   }
   last_congestion_window_ = current_congestion_window;
   last_update_time_ = current_time;
 
   if (!epoch_.IsInitialized()) {
     // First ACK after a loss event.
     DLOG(INFO) << "Start of epoch";
     epoch_ = current_time;  // Start of epoch.
@@ skipping 37 matching lines @@
   // Compute target congestion_window based on cubic target and estimated TCP
   // congestion_window, use highest (fastest).
   if (target_congestion_window < estimated_tcp_congestion_window_) {
     target_congestion_window = estimated_tcp_congestion_window_;
   }
   DLOG(INFO) << "Target congestion_window:" << target_congestion_window;
   return target_congestion_window;
 }
 
 }  // namespace net