Add a UMA histogram for type of web font usage

Source/core/fetch/FontResource.cpp

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile, Inc.
  *
  * 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
@@ skipping 28 matching lines @@
 #include "SVGNames.h"
 #include "core/dom/XMLDocument.h"
 #include "core/html/HTMLCollection.h"
 #include "core/svg/SVGFontElement.h"
 #endif
 
 namespace WebCore {
 
 static const double fontLoadWaitLimitSec = 3.0;
 
+enum FontPackageFormat {
+    PackageFormatUnknown,
+    PackageFormatSFNT,
+    PackageFormatWOFF,
+    PackageFormatWOFF2,
+    PackageFormatSVG,
+    PackageFormatEnumMax
+};
+
+static FontPackageFormat packageFormatOf(SharedBuffer* buffer)
+{
+    if (buffer->size() < 4)
+        return PackageFormatUnknown;
+
+    const char* data = buffer->data();
+    if (data[0] == 'w' && data[1] == 'O' && data[2] == 'F' && data[3] == 'F')
+        return PackageFormatWOFF;
+    if (data[0] == 'w' && data[1] == 'O' && data[2] == 'F' && data[3] == '2')
+        return PackageFormatWOFF2;
+    return PackageFormatSFNT;
+}
+
+static void recordPackageFormatHistogram(FontPackageFormat format)
+{
+    blink::Platform::current()->histogramEnumeration("WebFont.PackageFormat", format, PackageFormatEnumMax);
+}
+
 FontResource::FontResource(const ResourceRequest& resourceRequest)
     : Resource(resourceRequest, Font)
     , m_loadInitiated(false)
     , m_exceedsFontLoadWaitLimit(false)
     , m_fontLoadWaitLimitTimer(this, &FontResource::fontLoadWaitLimitCallback)
 {
 }
 
 FontResource::~FontResource()
 {
@@ skipping 25 matching lines @@
         while (FontResourceClient* client = walker.next())
             client->didStartFontLoad(this);
     }
 }
 
 bool FontResource::ensureCustomFontData()
 {
     if (!m_fontData && !errorOccurred() && !isLoading()) {
         if (m_data)
             m_fontData = FontCustomPlatformData::create(m_data.get());
-        if (!m_fontData)
+
+        if (m_fontData) {
+            recordPackageFormatHistogram(packageFormatOf(m_data.get()));
+        } else {
             setStatus(DecodeError);
+            recordPackageFormatHistogram(PackageFormatUnknown);
+        }
     }
     return m_fontData;
 }
 
 FontPlatformData FontResource::platformDataFromCustomData(float size, bool bold, bool italic, FontOrientation orientation, FontWidthVariant widthVariant)
 {
 #if ENABLE(SVG_FONTS)
     if (m_externalSVGDocument)
         return FontPlatformData(size, bold, italic);
 #endif
@@ skipping 10 matching lines @@
 
             OwnPtr<TextResourceDecoder> decoder = TextResourceDecoder::create("application/xml");
             String svgSource = decoder->decode(m_data->data(), m_data->size());
             svgSource = svgSource + decoder->flush();
 
             m_externalSVGDocument->setContent(svgSource);
 
             if (decoder->sawError())
                 m_externalSVGDocument = nullptr;
         }
-        if (!m_externalSVGDocument)
+        if (m_externalSVGDocument) {
+            recordPackageFormatHistogram(PackageFormatSVG);
+        } else {
             setStatus(DecodeError);
+            recordPackageFormatHistogram(PackageFormatUnknown);
+        }
     }
 
     return m_externalSVGDocument;
 }
 
 SVGFontElement* FontResource::getSVGFontById(const String& fontName) const
 {
     RefPtrWillBeRawPtr<HTMLCollection> collection = m_externalSVGDocument->getElementsByTagNameNS(SVGNames::fontTag.namespaceURI(), SVGNames::fontTag.localName());
     if (!collection)
         return 0;
@@ skipping 45 matching lines @@
 
 void FontResource::checkNotify()
 {
     m_fontLoadWaitLimitTimer.stop();
     ResourceClientWalker<FontResourceClient> w(m_clients);
     while (FontResourceClient* c = w.next())
         c->fontLoaded(this);
 }
 
 }