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

Source/core/css/CSSFontFace.h

 /*
  * Copyright (C) 2007, 2008 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 87 matching lines @@
         size_t size() const { return m_ranges.size(); }
         const UnicodeRange& rangeAt(size_t i) const { return m_ranges[i]; }
     private:
         Vector<UnicodeRange> m_ranges; // If empty, represents the whole code space.
     };
 
     FontFace::LoadStatus loadStatus() const { return m_fontFace->loadStatus(); }
     void willUseFontData(const FontDescription&);
     void load(const FontDescription&, CSSFontSelector* = 0);
 
+    bool hadBlankText() { return isValid() && m_sources.first()->hadBlankText(); }
+
 private:
     void setLoadStatus(FontFace::LoadStatus);
 
     UnicodeRangeSet m_ranges;
     CSSSegmentedFontFace* m_segmentedFontFace;
     Deque<OwnPtr<CSSFontFaceSource> > m_sources;
     FontFace* m_fontFace;
 };
 
 }
 
 #endif