Expose effective connection type to Cronet

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 1625 matching lines @@
 
 void NetworkQualityEstimator::MaybeRecomputeEffectiveConnectionType() {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   const base::TimeTicks now = tick_clock_->NowTicks();
   // Recompute effective connection type only if
   // |effective_connection_type_recomputation_interval_| has passed since it was
   // last computed or a connection change event was observed since the last
   // computation. Strict inequalities are used to ensure that effective
   // connection type is recomputed on connection change events even if the clock
-  // has not updated.
+  // has not updated. Recompute the effective connection type if the effective
+  // connection type was previously unavailable. This is because the RTT
+  // observations are voluminous, so it may now be possible to compute the
+  // effective connection type.
   if (now - last_effective_connection_type_computation_ <
           effective_connection_type_recomputation_interval_ &&
-      last_connection_change_ < last_effective_connection_type_computation_) {
+      last_connection_change_ < last_effective_connection_type_computation_ &&
+      effective_connection_type_ != EFFECTIVE_CONNECTION_TYPE_UNKNOWN) {
     return;
   }
 
   const EffectiveConnectionType past_type = effective_connection_type_;
   last_effective_connection_type_computation_ = now;
   effective_connection_type_ = GetEffectiveConnectionType();
 
   if (past_type != effective_connection_type_)
     NotifyObserversOfEffectiveConnectionTypeChanged();
 }
 
 void NetworkQualityEstimator::
     NotifyObserversOfEffectiveConnectionTypeChanged() {
   DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK_NE(EFFECTIVE_CONNECTION_TYPE_LAST, effective_connection_type_);
 
   // TODO(tbansal): Add hysteresis in the notification.
   FOR_EACH_OBSERVER(
       EffectiveConnectionTypeObserver, effective_connection_type_observer_list_,
       OnEffectiveConnectionTypeChanged(effective_connection_type_));
 }
 
 }  // namespace net