Move webfont usage metrics reporting to FontResource

Source/core/fetch/FontResource.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 32 matching lines @@
 class FontResource : public Resource {
 public:
     FontResource(const ResourceRequest&);
     virtual ~FontResource();
 
     virtual void load(ResourceFetcher*, const ResourceLoaderOptions&);
 
     virtual void didAddClient(ResourceClient*);
 
     virtual void allClientsRemoved();
+    void willUseFontData();
     void beginLoadIfNeeded(ResourceFetcher* dl);
     bool stillNeedsLoad() const { return !m_loadInitiated; }
 
     bool ensureCustomFontData();
     FontPlatformData platformDataFromCustomData(float size, bool bold, bool italic, FontOrientation = Horizontal, FontWidthVariant = RegularWidth);
 
 #if ENABLE(SVG_FONTS)
     bool ensureSVGFontData();
     SVGFontElement* getSVGFontById(const String&) const;
 #endif
 
 private:
     virtual void checkNotify();
     OwnPtr<FontCustomPlatformData> m_fontData;
     bool m_loadInitiated;
 
 #if ENABLE(SVG_FONTS)
     RefPtr<WebCore::SVGDocument> m_externalSVGDocument;
 #endif
+    class FontResourceHistograms {
+    public:
+        enum UsageType {
+            StyledAndUsed,
+            StyledButNotUsed,
+            NotStyledButUsed,
+            UsageTypeMax
+        };
+        FontResourceHistograms() : m_styledTime(0) { }
+        ~FontResourceHistograms();
+        void willUseFontData();
+        void loadStarted();
+    private:
+        double m_styledTime;
+    };
+    FontResourceHistograms m_histograms;
 
     friend class MemoryCache;
 };
 
 class FontResourceClient : public ResourceClient {
 public:
     virtual ~FontResourceClient() { }
     static ResourceClientType expectedType() { return FontType; }
     virtual ResourceClientType resourceClientType() const { return expectedType(); }
     virtual void fontLoaded(FontResource*) { }
     virtual void didStartFontLoad(FontResource*) { }
 };
 
 }
 
 #endif