Add DocumentTiming metrics for "time to first text paint"

Source/platform/fonts/FontFallbackList.h

 /*
  * Copyright (C) 2006, 2010 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 48 matching lines @@
         GlyphPages& m_pages;
         GlyphPageTreeNodeBase* m_pageZero;
     };
 
     static PassRefPtr<FontFallbackList> create() { return adoptRef(new FontFallbackList()); }
 
     ~FontFallbackList() { releaseFontData(); }
     bool isValid() const;
     void invalidate(PassRefPtrWillBeRawPtr<FontSelector>);
 
+    bool hasCustomFont() const { return m_hasCustomFont; }
     bool loadingCustomFonts() const;
     bool shouldSkipDrawing() const;
 
     FontSelector* fontSelector() const { return m_fontSelector.get(); }
     // FIXME: It should be possible to combine fontSelectorVersion and generation.
     unsigned fontSelectorVersion() const { return m_fontSelectorVersion; }
     unsigned generation() const { return m_generation; }
 
     CachingWordShaper& cachingWordShaper() const { return m_cachingWordShaper; }
 
@@ skipping 33 matching lines @@
     mutable Vector<RefPtr<FontData>, 1> m_fontList;
     GlyphPages m_pages;
     GlyphPageTreeNodeBase* m_pageZero;
     mutable const SimpleFontData* m_cachedPrimarySimpleFontData;
     RefPtrWillBePersistent<FontSelector> m_fontSelector;
     mutable CachingWordShaper m_cachingWordShaper;
     unsigned m_fontSelectorVersion;
     mutable int m_familyIndex;
     unsigned short m_generation;
     mutable bool m_hasLoadingFallback : 1;
+    mutable bool m_hasCustomFont : 1;
 };
 
 } // namespace blink
 
 #endif