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

Source/core/css/FontFaceSet.h

Index: Source/core/css/FontFaceSet.h
diff --git a/Source/core/css/FontFaceSet.h b/Source/core/css/FontFaceSet.h
index 082e897036dfc56c3f104f149bd06ebfd8c4d2cc..3303a26d1fb54c5d3031b94b7cd2c500a201c1dd 100644
--- a/Source/core/css/FontFaceSet.h
+++ b/Source/core/css/FontFaceSet.h
@@ -111,11 +111,14 @@ private:
 
     class FontLoadHistogram {
     public:
-        FontLoadHistogram() : m_count(0), m_recorded(false) { }
+        enum Status { NoWebFonts, HadBlankText, DidNotHaveBlankText, Reported };
+        FontLoadHistogram() : m_status(NoWebFonts), m_count(0), m_recorded(false) { }
         void incrementCount() { m_count++; }
+        void updateStatus(FontFace*);
         void record();
 
     private:
+        Status m_status;
         int m_count;
         bool m_recorded;
     };