Webfont CORS-enabled fetching with fallback

Source/core/css/RemoteFontFaceSource.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "core/css/RemoteFontFaceSource.h"
 
+#include "FetchInitiatorTypeNames.h"
 #include "core/css/CSSCustomFontData.h"
 #include "core/css/CSSFontFace.h"
+#include "core/css/CSSFontSelector.h"
+#include "core/fetch/ResourceFetcher.h"
 #include "platform/fonts/FontCache.h"
 #include "platform/fonts/FontDescription.h"
 #include "platform/fonts/SimpleFontData.h"
 #include "public/platform/Platform.h"
 #include "wtf/CurrentTime.h"
 
 namespace WebCore {
 
 RemoteFontFaceSource::RemoteFontFaceSource(FontResource* font)
     : m_font(font)
@@ skipping 55 matching lines @@
 
 void RemoteFontFaceSource::fontLoadWaitLimitExceeded(FontResource*)
 {
     pruneTable();
     if (m_face)
         m_face->fontLoadWaitLimitExceeded(this);
 
     m_histograms.recordFallbackTime(m_font.get());
 }
 
+void RemoteFontFaceSource::corsFailed(FontResource*)
+{
+    pruneTable();
+
+    if (m_face) {
+        Document* document = m_face->fontSelector() ? m_face->fontSelector()->document() : 0;
+        if (document) {
+            FetchRequest request(ResourceRequest(m_font->url()), FetchInitiatorTypeNames::css);
+            m_font->removeClient(this);

[Kunihiko Sakamoto, 2014/04/09 10:24:18]

CSSFontFaceSrcValue have a reference to this FontResource too, and we're not
updating it. I'm not sure if this may cause any problem or not.

[bashi, 2014/04/10 03:40:56]

Thank you for pointing this out. But it's difficult to update the reference
because RemoteFontFaceSource, which is the client of FontResource, can't reach
CSSFontFaceSrcValue when CORS failure occurs. Updating it will require
non-trivial change in css module and I'm not sure it is worth to do it for this
tentative logic.

I added an 'invalidator' which clears the reference in CSSFontFaceSrcValue so
that calling CSSFontFaceSrcValue::fetch() won't return invalid FontResource at
least. Does this make sense?

+            m_font = document->fetcher()->fetchFont(request);
+            m_font->addClient(this);
+            m_face->fontSelector()->beginLoadingFontSoon(m_font.get());
+        } else {
+            m_face->fontLoaded(this);
+        }
+    }
+}
+
 PassRefPtr<SimpleFontData> RemoteFontFaceSource::createFontData(const FontDescription& fontDescription)
 {
     if (!isLoaded())
         return createLoadingFallbackFontData(fontDescription);
 
     // Create new FontPlatformData from our CGFontRef, point size and ATSFontRef.
     if (!m_font->ensureCustomFontData())
         return nullptr;
 
     m_histograms.recordFallbackTime(m_font.get());
@@ skipping 54 matching lines @@
     if (m_loadStartTime > 0 && font && !font->isLoading()) {
         int duration = static_cast<int>(currentTimeMS() - m_loadStartTime);
         blink::Platform::current()->histogramCustomCounts(histogramName(font), duration, 0, 10000, 50);
         m_loadStartTime = -1;
 
         enum { Miss, Hit, DataUrl, CacheHitEnumMax };
         int histogramValue = font->url().protocolIsData() ? DataUrl
             : font->response().wasCached() ? Hit
             : Miss;
         blink::Platform::current()->histogramEnumeration("WebFont.CacheHit", histogramValue, CacheHitEnumMax);
+
+        if (!font->errorOccurred()) {
+            enum { CORSSuccess, CORSFail, CORSEnumMax };
+            int corsValue = font->options().corsEnabled == IsCORSEnabled ? CORSSuccess : CORSFail;
+            blink::Platform::current()->histogramEnumeration("WebFont.CORSSuccess", corsValue, CORSEnumMax);
+        }
     }
 }
 
 const char* RemoteFontFaceSource::FontLoadHistograms::histogramName(const FontResource* font)
 {
     if (font->errorOccurred())
         return "WebFont.DownloadTime.LoadError";
 
     unsigned size = font->encodedSize();
     if (size < 10 * 1024)
         return "WebFont.DownloadTime.0.Under10KB";
     if (size < 50 * 1024)
         return "WebFont.DownloadTime.1.10KBTo50KB";
     if (size < 100 * 1024)
         return "WebFont.DownloadTime.2.50KBTo100KB";
     if (size < 1024 * 1024)
         return "WebFont.DownloadTime.3.100KBTo1MB";
     return "WebFont.DownloadTime.4.Over1MB";
 }
 
 } // namespace WebCore