Persist HTTP RTT and Transport RTT estimates in UKM on navigation start.

chrome/browser/page_load_metrics/observers/ukm_page_load_metrics_observer.cc

Index: chrome/browser/page_load_metrics/observers/ukm_page_load_metrics_observer.cc
diff --git a/chrome/browser/page_load_metrics/observers/ukm_page_load_metrics_observer.cc b/chrome/browser/page_load_metrics/observers/ukm_page_load_metrics_observer.cc
index 43f863441e2a3447abc92eacca1fb4b90f5a6cdc..dd8aaf7efede949e515e3d3883c90526a37cc3a1 100644
--- a/chrome/browser/page_load_metrics/observers/ukm_page_load_metrics_observer.cc
+++ b/chrome/browser/page_load_metrics/observers/ukm_page_load_metrics_observer.cc
@@ -28,6 +28,9 @@ const char kUkmFailedProvisionaLoadName[] =
     "PageTiming.NavigationToFailedProvisionalLoad";
 const char kUkmEffectiveConnectionType[] =
     "Net.EffectiveConnectionType.OnNavigationStart";
+const char kUkmHttpRttEstimate[] = "Net.HttpRttEstimate.OnNavigationStart";
+const char kUkmTransportRttEstimate[] =
+    "Net.TransportRttEstimate.OnNavigationStart";
 const char kUkmNetErrorCode[] = "Net.ErrorCode.OnFailedProvisionalLoad";
 const char kUkmPageTransition[] = "Navigation.PageTransition";
 
@@ -81,6 +84,8 @@ UkmPageLoadMetricsObserver::ObservePolicy UkmPageLoadMetricsObserver::OnStart(
   if (network_quality_provider_) {
     effective_connection_type_ =
         network_quality_provider_->GetEffectiveConnectionType();
+    http_rtt_estimate_ = network_quality_provider_->GetHttpRTT();
+    transport_rtt_estimate_ = network_quality_provider_->GetTransportRTT();
   }
   page_transition_ = navigation_handle->GetPageTransition();
   return CONTINUE_OBSERVING;
@@ -187,6 +192,16 @@ void UkmPageLoadMetricsObserver::RecordPageLoadExtraInfoMetrics(
     builder->AddMetric(internal::kUkmEffectiveConnectionType,
                        static_cast<int64_t>(effective_connection_type_));
   }
+  if (http_rtt_estimate_) {
+    builder->AddMetric(
+        internal::kUkmHttpRttEstimate,
+        static_cast<int64_t>(http_rtt_estimate_.value().InMilliseconds()));
+  }
+  if (transport_rtt_estimate_) {
+    builder->AddMetric(
+        internal::kUkmTransportRttEstimate,
+        static_cast<int64_t>(transport_rtt_estimate_.value().InMilliseconds()));
+  }
   // page_transition_ fits in a uint32_t, so we can safely cast to int64_t.
   builder->AddMetric(internal::kUkmPageTransition,
                      static_cast<int64_t>(page_transition_));