Record RTT prediction accuracy when using average algorithms

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 e003654bb7e6da2b79efd21d07aac2e85fba8924..696e9b0e85d39c0e2095b90a48dc00a083f8efb2 100644
--- a/net/nqe/network_quality_estimator.h
+++ b/net/nqe/network_quality_estimator.h
@@ -17,6 +17,7 @@
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
+#include "base/optional.h"
 #include "base/threading/thread_checker.h"
 #include "base/time/time.h"
 #include "net/base/net_export.h"
@@ -320,6 +321,15 @@ class NET_EXPORT NetworkQualityEstimator
       bool add_default_platform_observations,
       const NetLogWithSource& net_log);
 
+  // Different experimental statistic algorithms that can be used for computing
+  // the predictions.
+  enum Statistic {
+    STATISTIC_WEIGHTED_AVERAGE = 0,
+    STATISTIC_UNWEIGHTED_AVERAGE = 1,
+    // Last statistic. Not to be used.
+    STATISTIC_LAST = 2
+  };
+
   // NetworkChangeNotifier::ConnectionTypeObserver implementation:
   void OnConnectionTypeChanged(
       NetworkChangeNotifier::ConnectionType type) override;
@@ -385,6 +395,27 @@ class NET_EXPORT NetworkQualityEstimator
   void OnUpdatedRTTAvailable(SocketPerformanceWatcherFactory::Protocol protocol,
                              const base::TimeDelta& rtt);
 
+  // Returns an estimate of network quality at the specified |percentile|.
+  // |disallowed_observation_sources| is the list of observation sources that
+  // should be excluded when computing the percentile.
+  // Only the observations later than |start_time| are taken into account.
+  // |percentile| must be between 0 and 100 (both inclusive) with higher
+  // percentiles indicating less performant networks. For example, if
+  // |percentile| is 90, then the network is expected to be faster than the
+  // returned estimate with 0.9 probability. Similarly, network is expected to
+  // be slower than the returned estimate with 0.1 probability. |statistic|
+  // is the statistic that should be used for computing the estimate. If unset,
+  // the default statistic is used. Virtualized for testing.
+  virtual base::TimeDelta GetRTTEstimateInternal(
+      const std::vector<NetworkQualityObservationSource>&
+          disallowed_observation_sources,
+      base::TimeTicks start_time,
+      const base::Optional<Statistic>& statistic,
+      int percentile) const;
+  int32_t GetDownlinkThroughputKbpsEstimateInternal(
+      const base::TimeTicks& start_time,
+      int percentile) const;
+
  private:
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest,
                            AdaptiveRecomputationEffectiveConnectionType);
@@ -483,24 +514,6 @@ class NET_EXPORT NetworkQualityEstimator
   // current connection type to the observation buffer.
   void AddDefaultEstimates();
 
-  // Returns an estimate of network quality at the specified |percentile|.
-  // |disallowed_observation_sources| is the list of observation sources that
-  // should be excluded when computing the percentile.
-  // Only the observations later than |start_time| are taken into account.
-  // |percentile| must be between 0 and 100 (both inclusive) with higher
-  // percentiles indicating less performant networks. For example, if
-  // |percentile| is 90, then the network is expected to be faster than the
-  // returned estimate with 0.9 probability. Similarly, network is expected to
-  // be slower than the returned estimate with 0.1 probability.
-  base::TimeDelta GetRTTEstimateInternal(
-      const std::vector<NetworkQualityObservationSource>&
-          disallowed_observation_sources,
-      const base::TimeTicks& start_time,
-      int percentile) const;
-  int32_t GetDownlinkThroughputKbpsEstimateInternal(
-      const base::TimeTicks& start_time,
-      int percentile) const;
-
   // Returns the current network ID checking by calling the platform APIs.
   // Virtualized for testing.
   virtual nqe::internal::NetworkID GetCurrentNetworkID() const;
@@ -606,6 +619,8 @@ class NET_EXPORT NetworkQualityEstimator
       const nqe::internal::NetworkID& network_id,
       const nqe::internal::CachedNetworkQuality& cached_network_quality);
 
+  const char* GetNameForStatistic(int i) const;
+
   // Determines if the requests to local host can be used in estimating the
   // network quality. Set to true only for tests.
   bool use_localhost_requests_;
@@ -689,6 +704,10 @@ class NET_EXPORT NetworkQualityEstimator
   nqe::internal::NetworkQuality estimated_quality_at_last_main_frame_;
   EffectiveConnectionType effective_connection_type_at_last_main_frame_;
 
+  // Estimated RTT at HTTP layer when the last main frame transaction was
+  // started. Computed using different statistics.
+  base::TimeDelta http_rtt_at_last_main_frame_[STATISTIC_LAST];
+
   // Estimated network quality obtained from external estimate provider when the
   // external estimate provider was last queried.
   nqe::internal::NetworkQuality external_estimate_provider_quality_;