Expose RTT and downlink bandwidth using experimental Javascript API

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 b68636a32525687261cc8d298c5a8beefbbf101f..e92bac4157c873d101d56583a2136fd3e99dcba0 100644
--- a/net/nqe/network_quality_estimator.h
+++ b/net/nqe/network_quality_estimator.h
@@ -341,6 +341,9 @@ class NET_EXPORT NetworkQualityEstimator
       const std::map<nqe::internal::NetworkID,
                      nqe::internal::CachedNetworkQuality> read_prefs);
 
+  // Prevents |this| from sending any notifications to the observers.
+  void SuppressNotificationsForTesting();
+
  protected:
   // A protected constructor for testing that allows setting the value of
   // |add_default_platform_observations_|.
@@ -809,6 +812,9 @@ class NET_EXPORT NetworkQualityEstimator
   const std::vector<NetworkQualityObservationSource>
       disallowed_observation_sources_for_transport_;
 
+  // If true, notifications are not sent to any of the observers.
+  bool suppress_notifications_for_testing_;
+
   base::WeakPtrFactory<NetworkQualityEstimator> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(NetworkQualityEstimator);