NQE: Add accuracy histogram for external estimate provider

net/nqe/network_quality_estimator.h

 // 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.
 
 #ifndef NET_NQE_NETWORK_QUALITY_ESTIMATOR_H_
 #define NET_NQE_NETWORK_QUALITY_ESTIMATOR_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 407 matching lines @@
 
   // Maximum size of the cache that holds network quality estimates.
   // Smaller size may reduce the cache hit rate due to frequent evictions.
   // Larger size may affect performance.
   static const size_t kMaximumNetworkQualityCacheSize = 10;
 
   // Returns the RTT value to be used when the valid RTT is unavailable. Readers
   // should discard RTT if it is set to the value returned by |InvalidRTT()|.
   static const base::TimeDelta InvalidRTT();
 
+  // Queries external estimate provider for network quality. When the network
+  // quality is available, OnUpdatedEstimateAvailable() is called.
+  void MaybeQueryExternalEstimateProvider() const;
+
   // Records UMA when there is a change in connection type.
   void RecordMetricsOnConnectionTypeChanged() const;
 
   // Records UMA on main frame requests.
   void RecordMetricsOnMainFrameRequest() const;
 
   // Records a downstream throughput observation to the observation buffer if
   // a valid observation is available. |downstream_kbps| is the downstream
   // throughput in kilobits per second.
   void OnNewThroughputObservationAvailable(int32_t downstream_kbps);
@@ skipping 166 matching lines @@
       connection_thresholds_[EFFECTIVE_CONNECTION_TYPE_LAST];
 
   // Latest time when the headers for a main frame request were received.
   base::TimeTicks last_main_frame_request_;
 
   // Estimated network quality when the response headers for the last mainframe
   // request were received.
   nqe::internal::NetworkQuality estimated_quality_at_last_main_frame_;
   EffectiveConnectionType effective_connection_type_at_last_main_frame_;
 
+  // Estimated network quality obtained from external estimate provider when the
+  // external estimate provider was last queried.
+  nqe::internal::NetworkQuality external_estimate_provider_quality_;
+
   // ExternalEstimateProvider that provides network quality using operating
   // system APIs. May be NULL.
   const std::unique_ptr<ExternalEstimateProvider> external_estimate_provider_;
 
   // Observer list for changes in effective connection type.
   base::ObserverList<EffectiveConnectionTypeObserver>
       effective_connection_type_observer_list_;
 
   // Observer lists for round trip times and throughput measurements.
   base::ObserverList<RTTObserver> rtt_observer_list_;
@@ skipping 21 matching lines @@
   base::ThreadChecker thread_checker_;
 
   base::WeakPtrFactory<NetworkQualityEstimator> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(NetworkQualityEstimator);
 };
 
 }  // namespace net
 
 #endif  // NET_NQE_NETWORK_QUALITY_ESTIMATOR_H_