NQE: Allow algorithm to be set using variation params

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 57cf98b686864121b3e182072a49cc47a75ed2ba..d11b4841628cec93f6b83ffb75f15e6cd50f8035 100644
--- a/net/nqe/network_quality_estimator.h
+++ b/net/nqe/network_quality_estimator.h
@@ -322,6 +322,8 @@ class NET_EXPORT_PRIVATE NetworkQualityEstimator
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, StoreObservations);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, TestAddObservation);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, ObtainOperatingParams);
+  FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest,
+                           ObtainAlgorithmToUseFromParams);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, HalfLifeParam);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, ComputedPercentiles);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, TestCaching);
@@ -346,6 +348,23 @@ class NET_EXPORT_PRIVATE NetworkQualityEstimator
   typedef std::map<NetworkID, nqe::internal::CachedNetworkQuality>
       CachedNetworkQualities;
 
+  // Algorithms supported by network quality estimator for computing effective
+  // connection type.
+  enum class EffectiveConnectionTypeAlgorithm {
+    HTTP_RTT_AND_DOWNSTREAM_THROUGHOUT = 0,
+    EFFECTIVE_CONNECTION_TYPE_ALGORITHM_LAST
+  };
+
+  // Map from algorithm names to EffectiveConnectionTypeAlgorithm.
+  const std::map<std::string, EffectiveConnectionTypeAlgorithm>
+      algorithm_name_to_enum_;
+
+  // The default algorithm to be used if the algorithm value is not available
+  // through field trial parameters.
+  static const EffectiveConnectionTypeAlgorithm
+      kDefaultEffectiveConnectionTypeAlgorithm =
+          EffectiveConnectionTypeAlgorithm::HTTP_RTT_AND_DOWNSTREAM_THROUGHOUT;
+
   // Minimum valid value of the variation parameter that holds RTT (in
   // milliseconds) values.
   static const int kMinimumRTTVariationParameterMsec = 1;
@@ -443,6 +462,14 @@ class NET_EXPORT_PRIVATE NetworkQualityEstimator
   // main frame request is observed.
   void RecordAccuracyAfterMainFrame(base::TimeDelta measuring_duration) const;
 
+  // Returns the effective type of the current connection based on only the
+  // samples observed after |start_time|. Uses HTTP RTT and downstream
+  // throughput to compute the effective connection type, and requires both of
+  // them to have a valid value.
+  EffectiveConnectionType
+  GetRecentEffectiveConnectionTypeHttpRTTAndDownstreamThroughput(
+      const base::TimeTicks& start_time) const;
+
   // Values of external estimate provider status. This enum must remain
   // synchronized with the enum of the same name in
   // metrics/histograms/histograms.xml.
@@ -473,6 +500,12 @@ class NET_EXPORT_PRIVATE NetworkQualityEstimator
   // The factor by which the weight of an observation reduces every second.
   const double weight_multiplier_per_second_;
 
+  // Algorithm to use for computing effective connection type. The value is
+  // obtained from field trial parameters. If the value from field trial
+  // parameters is unavailable, it is set to
+  // kDefaultEffectiveConnectionTypeAlgorithm.
+  const EffectiveConnectionTypeAlgorithm effective_connection_type_algorithm_;
+
   // Tick clock used by the network quality estimator.
   std::unique_ptr<base::TickClock> tick_clock_;