Expose cellular signal strength on Android to native

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 459 matching lines @@
 
   // Notify observers of a change in effective connection type.
   void NotifyObserversOfEffectiveConnectionTypeChanged();
 
   // Records NQE accuracy metrics. |measuring_duration| should belong to the
   // vector returned by AccuracyRecordingIntervals().
   // RecordAccuracyAfterMainFrame should be called |measuring_duration| after a
   // main frame request is observed.
   void RecordAccuracyAfterMainFrame(base::TimeDelta measuring_duration) const;
 
+  // Obtains the current cellular signal strength value and updates
+  // |min_signal_strength_since_connection_change_| and
+  // |max_signal_strength_since_connection_change_|.
+  void UpdateSignalStrength();
+
   // 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
@@ skipping 109 matching lines @@
   // |downstream_throughput_kbps_observations_|, which are later used for
   // estimating the throughput.
   std::unique_ptr<nqe::internal::ThroughputAnalyzer> throughput_analyzer_;
 
   // 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
   // |effective_connection_type_recomputation_interval_| ago).
   EffectiveConnectionType effective_connection_type_;
 
+  // Minimum and Maximum signal strength (in dbM) observed since last connection
+  // change. Updated on connection change and main frame requests.
+  int32_t min_signal_strength_since_connection_change_;
+  int32_t max_signal_strength_since_connection_change_;
+
   base::ThreadChecker thread_checker_;
 
   base::WeakPtrFactory<NetworkQualityEstimator> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(NetworkQualityEstimator);
 };
 
 }  // namespace net
 
 #endif  // NET_NQE_NETWORK_QUALITY_ESTIMATOR_H_