Make kbps optional when computing effective connection type

net/nqe/network_quality_estimator.cc

 // Copyright 2015 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/nqe/network_quality_estimator.h"
 
 #include <algorithm>
 #include <cmath>
 #include <limits>
 #include <utility>
@@ skipping 1083 matching lines @@
   DCHECK(thread_checker_.CalledOnValidThread());
 
   if (effective_connection_type_algorithm_ ==
       EffectiveConnectionTypeAlgorithm::HTTP_RTT_AND_DOWNSTREAM_THROUGHOUT) {
     return GetRecentEffectiveConnectionTypeUsingMetrics(
         start_time, NetworkQualityEstimator::MetricUsage::
                         MUST_BE_USED /* http_rtt_metric */,
         NetworkQualityEstimator::MetricUsage::
             DO_NOT_USE /* transport_rtt_metric */,
         NetworkQualityEstimator::MetricUsage::
-            MUST_BE_USED /* downstream_throughput_kbps_metric */,
+            USE_IF_AVAILABLE /* downstream_throughput_kbps_metric */,
         http_rtt, transport_rtt, downstream_throughput_kbps);
   }
   if (effective_connection_type_algorithm_ ==
       EffectiveConnectionTypeAlgorithm::
           TRANSPORT_RTT_OR_DOWNSTREAM_THROUGHOUT) {
     return GetRecentEffectiveConnectionTypeUsingMetrics(
         start_time,
         NetworkQualityEstimator::MetricUsage::DO_NOT_USE /* http_rtt_metric */,
         NetworkQualityEstimator::MetricUsage::
             USE_IF_AVAILABLE /* transport_rtt_metric */,
@@ skipping 609 matching lines @@
         NETWORK_QUALITY_OBSERVATION_SOURCE_HTTP_CACHED_ESTIMATE);
     downstream_throughput_kbps_observations_.AddObservation(
         throughput_observation);
     NotifyObserversOfThroughput(throughput_observation);
   }
 
   ComputeEffectiveConnectionType();
 }
 
 }  // namespace net