Fix problems with absolute value function.

net/quic/congestion_control/tcp_cubic_sender.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/tcp_cubic_sender.h"
 
 #include <algorithm>
 
 #include "base/metrics/histogram.h"
 
@@ skipping 322 matching lines @@
     delay_min_ = rtt;
   }
   // First time call.
   if (smoothed_rtt_.IsZero()) {
     smoothed_rtt_ = rtt;
     mean_deviation_ = QuicTime::Delta::FromMicroseconds(
         rtt.ToMicroseconds() / 2);
   } else {
     mean_deviation_ = QuicTime::Delta::FromMicroseconds(
         kOneMinusBeta * mean_deviation_.ToMicroseconds() +
-        kBeta * abs(smoothed_rtt_.ToMicroseconds() - rtt.ToMicroseconds()));
+        kBeta *
+            std::abs(smoothed_rtt_.ToMicroseconds() - rtt.ToMicroseconds()));
     smoothed_rtt_ = QuicTime::Delta::FromMicroseconds(
         kOneMinusAlpha * smoothed_rtt_.ToMicroseconds() +
         kAlpha * rtt.ToMicroseconds());
     DVLOG(1) << "Cubic; smoothed_rtt_:" << smoothed_rtt_.ToMicroseconds()
                << " mean_deviation_:" << mean_deviation_.ToMicroseconds();
   }
 
   // Hybrid start triggers when cwnd is larger than some threshold.
   if (congestion_window_ <= slowstart_threshold_ &&
       congestion_window_ >= kHybridStartLowWindow) {
     if (!hybrid_slow_start_.started()) {
       // Time to start the hybrid slow start.
       hybrid_slow_start_.Reset(end_sequence_number_);
     }
     hybrid_slow_start_.Update(rtt, delay_min_);
     if (hybrid_slow_start_.Exit()) {
       slowstart_threshold_ = congestion_window_;
     }
   }
 }
 
 }  // namespace net