Add metrics for style update time before FCP.

third_party/WebKit/Source/core/timing/PerformanceTiming.cpp

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 395 matching lines @@
 unsigned long long PerformanceTiming::authorStyleSheetParseDurationBeforeFCP()
     const {
   const CSSTiming* timing = cssTiming();
   if (!timing)
     return 0;
 
   return toIntegerMilliseconds(
       timing->authorStyleSheetParseDurationBeforeFCP());
 }
 
+unsigned long long PerformanceTiming::updateStyleDurationBeforeFCP() const {
+  const CSSTiming* timing = cssTiming();
+  if (!timing)
+    return 0;
+
+  return toIntegerMilliseconds(timing->updateDurationBeforeFCP());
+}
+
 DocumentLoader* PerformanceTiming::documentLoader() const {
   if (!frame())
     return nullptr;
 
   return frame()->loader().documentLoader();
 }
 
 const DocumentTiming* PerformanceTiming::documentTiming() const {
   if (!frame())
     return nullptr;
@@ skipping 100 matching lines @@
 
   return timing->pseudoWallTimeToMonotonicTime(
       toDoubleSeconds(integerMilliseconds));
 }
 
 DEFINE_TRACE(PerformanceTiming) {
   DOMWindowProperty::trace(visitor);
 }
 
 }  // namespace blink