Add NavigationToFirstContentfulPaint UMA for ServiceWorker controlled pages.

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 78 matching lines @@
     DocumentLoadTiming* timing = documentLoadTiming();
     if (!timing)
         return 0;
 
     if (timing->hasCrossOriginRedirect() || !timing->hasSameOriginAsPreviousDocument())
         return 0;
 
     return monotonicTimeToIntegerMilliseconds(timing->unloadEventEnd());
 }
 
+unsigned long long PerformanceTiming::workerStart() const
+{
+    ResourceLoadTiming* timing = resourceLoadTiming();
+    if (!timing)
+        return 0;
+
+    return monotonicTimeToIntegerMilliseconds(timing->workerStart());
+}
+
 unsigned long long PerformanceTiming::redirectStart() const
 {
     DocumentLoadTiming* timing = documentLoadTiming();
     if (!timing)
         return 0;
 
     if (timing->hasCrossOriginRedirect())
         return 0;
 
     return monotonicTimeToIntegerMilliseconds(timing->redirectStart());
@@ skipping 395 matching lines @@
 
     return timing->pseudoWallTimeToMonotonicTime(toDoubleSeconds(integerMilliseconds));
 }
 
 DEFINE_TRACE(PerformanceTiming)
 {
     DOMWindowProperty::trace(visitor);
 }
 
 } // namespace blink