Add metrics for style update time before FCP.

chrome/renderer/page_load_metrics/metrics_render_frame_observer.cc

Index: chrome/renderer/page_load_metrics/metrics_render_frame_observer.cc
diff --git a/chrome/renderer/page_load_metrics/metrics_render_frame_observer.cc b/chrome/renderer/page_load_metrics/metrics_render_frame_observer.cc
index a705b61ff00a13576fbfac6652d246387856a37d..006eda7b705f3eafe5aa4a37ca654a8c37077421 100644
--- a/chrome/renderer/page_load_metrics/metrics_render_frame_observer.cc
+++ b/chrome/renderer/page_load_metrics/metrics_render_frame_observer.cc
@@ -150,6 +150,10 @@ PageLoadTiming MetricsRenderFrameObserver::GetTiming() const {
         base::TimeDelta::FromSecondsD(
             perf.authorStyleSheetParseDurationBeforeFCP());
   }
+  if (perf.updateStyleDurationBeforeFCP() > 0.0) {
+    timing.style_sheet_timing.update_style_duration_before_fcp =
+        base::TimeDelta::FromSecondsD(perf.updateStyleDurationBeforeFCP());
+  }
   return timing;
 }