Expose cellular signal strength on Android to native

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..e4c16af836878d659dfcf418b8b709b3abb05c6a 100644
--- a/net/nqe/network_quality_estimator.h
+++ b/net/nqe/network_quality_estimator.h
@@ -443,6 +443,11 @@ class NET_EXPORT_PRIVATE NetworkQualityEstimator
   // main frame request is observed.
   void RecordAccuracyAfterMainFrame(base::TimeDelta measuring_duration) const;
 
+  // Obtains the current cellular RSSI value and updates
+  // |min_rssi_since_connection_change_| and
+  // |max_rssi_since_connection_change_|.
+  void UpdateSignalStrength();
+
   // Values of external estimate provider status. This enum must remain
   // synchronized with the enum of the same name in
   // metrics/histograms/histograms.xml.
@@ -557,6 +562,11 @@ class NET_EXPORT_PRIVATE NetworkQualityEstimator
   // |effective_connection_type_recomputation_interval_| ago).
   EffectiveConnectionType effective_connection_type_;
 
+  // Minimum and Maximum RSSI observed since last connection change. Updated
+  // on connection change and main frame requests.
+  int32_t min_rssi_since_connection_change_;
+  int32_t max_rssi_since_connection_change_;
+
   base::ThreadChecker thread_checker_;
 
   base::WeakPtrFactory<NetworkQualityEstimator> weak_ptr_factory_;