Add metrics for style update time before FCP.

third_party/WebKit/Source/web/WebPerformance.cpp

Index: third_party/WebKit/Source/web/WebPerformance.cpp
diff --git a/third_party/WebKit/Source/web/WebPerformance.cpp b/third_party/WebKit/Source/web/WebPerformance.cpp
index 3b3bee457615884254cb04d74ca28ab6ee80b27a..6336020b6c0cc40d8eac4bede20db368058896fd 100644
--- a/third_party/WebKit/Source/web/WebPerformance.cpp
+++ b/third_party/WebKit/Source/web/WebPerformance.cpp
@@ -202,6 +202,11 @@ double WebPerformance::authorStyleSheetParseDurationBeforeFCP() const {
       m_private->timing()->authorStyleSheetParseDurationBeforeFCP());
 }
 
+double WebPerformance::updateStyleDurationBeforeFCP() const {
+  return millisecondsToSeconds(
+      m_private->timing()->updateStyleDurationBeforeFCP());
+}
+
 WebPerformance::WebPerformance(Performance* performance)
     : m_private(performance) {}