Compute effective connection type dynamically

net/nqe/network_quality_estimator.h

Index: net/nqe/network_quality_estimator.h
diff --git a/net/nqe/network_quality_estimator.h b/net/nqe/network_quality_estimator.h
index 973b92579bb653fa452e25dc3a6f6c19cff57785..b4ff50723adc8460689d21d585ef36f09d402a1f 100644
--- a/net/nqe/network_quality_estimator.h
+++ b/net/nqe/network_quality_estimator.h
@@ -295,6 +295,8 @@ class NET_EXPORT NetworkQualityEstimator
   virtual double RandDouble() const;
 
  private:
+  FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest,
+                           AdaptiveRecomputationEffectiveConnectionType);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, StoreObservations);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, TestAddObservation);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, ObtainOperatingParams);
@@ -305,6 +307,8 @@ class NET_EXPORT NetworkQualityEstimator
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, TestGetMetricsSince);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest,
                            TestExternalEstimateProviderMergeEstimates);
+  FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest,
+                           UnknownEffectiveConnectionType);
 
   // Value of round trip time observations is in base::TimeDelta.
   typedef nqe::internal::Observation<base::TimeDelta> RttObservation;
@@ -508,13 +512,6 @@ class NET_EXPORT NetworkQualityEstimator
   // Tick clock used by the network quality estimator.
   std::unique_ptr<base::TickClock> tick_clock_;
 
-  // Minimum duration between two consecutive computations of effective
-  // connection type. Set to non-zero value as a performance optimization.
-  const base::TimeDelta effective_connection_type_recomputation_interval_;
-
-  // Time when the effective connection type was last computed.
-  base::TimeTicks last_effective_connection_type_computation_;
-
   // Intervals after the main frame request arrives at which accuracy of network
   // quality prediction is recorded.
   std::vector<base::TimeDelta> accuracy_recording_intervals_;
@@ -591,6 +588,18 @@ class NET_EXPORT NetworkQualityEstimator
   // estimating the throughput.
   std::unique_ptr<nqe::internal::ThroughputAnalyzer> throughput_analyzer_;
 
+  // Minimum duration between two consecutive computations of effective
+  // connection type. Set to non-zero value as a performance optimization.
+  const base::TimeDelta effective_connection_type_recomputation_interval_;
+
+  // Time when the effective connection type was last computed.
+  base::TimeTicks last_effective_connection_type_computation_;
+
+  // Number of RTT and bandwidth samples available when effective connection
+  // type was last recomputed.
+  size_t number_of_rtt_samples_at_last_ect_computation_;
+  size_t number_of_bandwidth_samples_at_last_ect_computation_;

[RyanSturm, 2016/08/08 23:57:01]

nit: The naming of this variable is mouthful and has nothing in common with
downstream_throughput_kbps_observations_, which makes it confusing. I think that
the number_of_ part is unnecessary.

Maybe, throughput_observations_size_at_last_ect_computation_? If you want to
refactor the observations buffer name to bandwidth, that also works.

If you do decide to change this, make the rtt consistent with that change.

[tbansal1, 2016/08/09 18:00:56]

Done.

+
   // Current effective connection type. It is updated on connection change
   // events. It is also updated every time there is network traffic (provided
   // the last computation was more than