Add DocumentTiming metrics for "time to first text paint"

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 304 matching lines @@
 
 unsigned long long PerformanceTiming::firstLayout() const
 {
     const DocumentTiming* timing = documentTiming();
     if (!timing)
         return 0;
 
     return monotonicTimeToIntegerMilliseconds(timing->firstLayout());
 }
 
+unsigned long long PerformanceTiming::firstNonBlankText() const
+{
+    const DocumentTiming* timing = documentTiming();
+    if (!timing)
+        return 0;
+
+    return monotonicTimeToIntegerMilliseconds(timing->firstNonBlankText());
+}
+
+unsigned long long PerformanceTiming::firstCustomFontText() const
+{
+    const DocumentTiming* timing = documentTiming();
+    if (!timing)
+        return 0;
+
+    return monotonicTimeToIntegerMilliseconds(timing->firstCustomFontText());
+}
+
 DocumentLoader* PerformanceTiming::documentLoader() const
 {
     if (!m_frame)
         return nullptr;
 
     return m_frame->loader().documentLoader();
 }
 
 const DocumentTiming* PerformanceTiming::documentTiming() const
 {
@@ skipping 70 matching lines @@
 
     return timing->pseudoWallTimeToMonotonicTime(toDoubleSeconds(integerMilliseconds));
 }
 
 DEFINE_TRACE(PerformanceTiming)
 {
     DOMWindowProperty::trace(visitor);
 }
 
 } // namespace blink