Use removeFontFace to avoid resetting fontSelector.

Source/core/dom/StyleEngine.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) Research In Motion Limited 2010-2011. All rights reserved.
@@ skipping 517 matching lines @@
     m_didCalculateResolver = true;
     if (m_document.didLayoutWithPendingStylesheets() && !hasPendingSheets())
         change.setNeedsRepaint();
 
     if (updateActiveStyleSheets(mode))
         change.setNeedsStyleRecalc();
 
     return change;
 }
 
-void StyleEngine::resetFontSelector()
+void StyleEngine::clearFontCache()
+{
+    // We should not recreate FontSelector. Instead, clear fontFaceCache.
+    if (m_fontSelector)
+        m_fontSelector->fontFaceCache()->clear();
+    if (m_resolver)
+        m_resolver->invalidateMatchedPropertiesCache();
+}
+
+void StyleEngine::updateGenericFontFamilySettings()

[dglazkov, 2014/01/29 05:11:50]

Why do we need a separate function for this? When is this called?

[tasak, 2014/01/29 10:13:43]

The updateGenericFontFamilySettings will be invoked from WebSettings or
InternalSettings.

clearFontCache will be invoked from updateActiveStyleSheets when we update some
stylesheets which contains @font-face rule.

 {
     if (!m_fontSelector)
         return;
 
-    m_fontSelector->clearDocument();
-    if (m_resolver) {
-        m_fontSelector->unregisterForInvalidationCallbacks(m_resolver.get());
+    m_fontSelector->updateGenericFontFamilySettings(m_document);
+    if (m_resolver)
         m_resolver->invalidateMatchedPropertiesCache();
-    }
+}
 
-    // If the document has been already detached, we don't need to recreate
-    // CSSFontSelector.
-    if (m_document.isActive()) {
-        m_fontSelector = CSSFontSelector::create(&m_document);
-        if (m_resolver)
-            m_fontSelector->registerForInvalidationCallbacks(m_resolver.get());
-    } else {
-        m_fontSelector = 0;
-    }
+void StyleEngine::removeFontFaceRules(const Vector<const StyleRuleFontFace*>& fontFaceRules)
+{
+    if (!m_fontSelector)
+        return;
+
+    CSSSegmentedFontFaceCache* cache = m_fontSelector->fontFaceCache();
+    for (unsigned i = 0; i < fontFaceRules.size(); ++i)
+        cache->remove(fontFaceRules[i]);
+    if (m_resolver)
+        m_resolver->invalidateMatchedPropertiesCache();
 }
 
 void StyleEngine::markTreeScopeDirty(TreeScope& scope)
 {
     if (scope == m_document) {
         markDocumentDirty();
         return;
     }
 
     m_dirtyTreeScopes.add(&scope);
@@ skipping 48 matching lines @@
 {
     HashMap<StyleSheetContents*, AtomicString>::iterator it = sheetToTextCache().find(contents);
     if (it == sheetToTextCache().end())
         return;
 
     textToSheetCache().remove(it->value);
     sheetToTextCache().remove(contents);
 }
 
 }