UMA histograms to measure whether / how long blank text is rendered for loading web fonts

Source/core/css/CSSFontFaceSource.h

 /*
  * Copyright (C) 2007, 2008, 2011 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 56 matching lines @@
     SVGFontFaceElement* svgFontFaceElement() const;
     void setSVGFontFaceElement(PassRefPtr<SVGFontFaceElement>);
     bool isSVGFontFaceSource() const;
     void setHasExternalSVGFont(bool value) { m_hasExternalSVGFont = value; }
 #endif
 
     bool ensureFontData();
     bool isLocalFontAvailable(const FontDescription&);
     void beginLoadIfNeeded();
 
+    // For UMA reporting
+    void paintRequested() { m_histograms.fallbackFontPainted(); }
+    bool hadBlankText() { return m_histograms.hadBlankText(); }
+
 private:
     typedef HashMap<unsigned, RefPtr<SimpleFontData> > FontDataTable; // The hash key is composed of size synthetic styles.
 
     class FontLoadHistograms {
     public:
-        FontLoadHistograms() : m_loadStartTime(0) { }
+        FontLoadHistograms() : m_loadStartTime(0), m_fallbackPaintTime(0) { }
         void loadStarted();
+        void fallbackFontPainted();
         void recordLocalFont(bool loadSuccess);
         void recordRemoteFont(const FontResource*);
+        void recordFallbackTime(const FontResource*);
+        bool hadBlankText() { return m_fallbackPaintTime; }
     private:
         const char* histogramName(const FontResource*);
         double m_loadStartTime;
+        double m_fallbackPaintTime;
     };
 
     void pruneTable();
     void startLoadingTimerFired(Timer<CSSFontFaceSource>*);
 
     AtomicString m_string; // URI for remote, built-in font name for local.
     ResourcePtr<FontResource> m_font; // For remote fonts, a pointer to our cached resource.
     CSSFontFace* m_face; // Our owning font face.
     FontDataTable m_fontDataTable;
     FontLoadHistograms m_histograms;
 
 #if ENABLE(SVG_FONTS)
     RefPtr<SVGFontFaceElement> m_svgFontFaceElement;
     RefPtr<SVGFontElement> m_externalSVGFontElement;
     bool m_hasExternalSVGFont;
 #endif
 };
 
 }
 
 #endif