Fix QUIC's SendAlgorithmSimulator to fix an off by 1 error in the buffer

net/quic/congestion_control/send_algorithm_simulator.cc

 // Copyright 2014 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/send_algorithm_simulator.h"
 
 #include <limits>
 
 #include "base/logging.h"
 #include "base/rand_util.h"
@@ skipping 220 matching lines @@
     if (!sent_packets_.empty() &&
         !sent_packets_.back().ack_time.IsInitialized() &&
         loss_correlation_ * kuint64max > simple_random_.RandUint64()) {
       packet_lost = true;
     }
 
     QuicTime ack_time = clock_->Now().Add(rtt_);
     // If the number of bytes in flight are less than the bdp, there's
     // no buffering delay.  Bytes lost from the buffer are not counted.
     QuicByteCount bdp = bandwidth_.ToBytesPerPeriod(rtt_);
-    if (sent_packets_.size() * kPacketSize > bdp) {
-      QuicByteCount qsize = sent_packets_.size() * kPacketSize - bdp;
+    if ((sent_packets_.size() + 1) * kPacketSize > bdp) {
+      QuicByteCount qsize = (sent_packets_.size() + 1) * kPacketSize - bdp;
       ack_time = ack_time.Add(bandwidth_.TransferTime(qsize));
     }
     // If the packet is lost, give it an ack time of Zero.
     sent_packets_.push_back(SentPacket(
         next_sent_, clock_->Now(), packet_lost ? QuicTime::Zero() : ack_time));
   }
   ++next_sent_;
   bytes_in_flight_ += kPacketSize;
 }
 
@@ skipping 11 matching lines @@
 void SendAlgorithmSimulator::AdvanceTime(QuicTime::Delta delta) {
   clock_->AdvanceTime(delta);
 }
 
 // Elapsed time from the start of the connection.
 QuicTime SendAlgorithmSimulator::ElapsedTime() {
   return clock_->Now();
 }
 
 }  // namespace net