Do not block painting for in-body CSS

third_party/WebKit/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 113 matching lines @@
     m_maxDirectAdjacentSelectors = features.maxDirectAdjacentSelectors();
 }
 
 void StyleEngine::injectAuthorSheet(StyleSheetContents* authorSheet)
 {
     m_injectedAuthorStyleSheets.append(CSSStyleSheet::create(authorSheet, m_document));
     markDocumentDirty();
     resolverChanged(AnalyzedStyleUpdate);
 }
 
-void StyleEngine::addPendingSheet()
+void StyleEngine::addPendingSheet(bool isBeforeBody)
 {
     m_pendingStylesheets++;
+    if (isBeforeBody)
+        m_pendingRenderBlockingStylesheets++;
 }
 
 // This method is called whenever a top-level stylesheet has finished loading.
-void StyleEngine::removePendingSheet(Node* styleSheetCandidateNode)
+void StyleEngine::removePendingSheet(Node* styleSheetCandidateNode, bool isBeforeBody)
 {
     DCHECK(styleSheetCandidateNode);
     TreeScope* treeScope = isStyleElement(*styleSheetCandidateNode) ? &styleSheetCandidateNode->treeScope() : m_document.get();
     if (styleSheetCandidateNode->inShadowIncludingDocument())
         markTreeScopeDirty(*treeScope);
 
+    if (isBeforeBody) {
+        DCHECK_GT(m_pendingRenderBlockingStylesheets, 0);
+        m_pendingRenderBlockingStylesheets--;
+    }
+
     // Make sure we knew this sheet was pending, and that our count isn't out of sync.
     DCHECK_GT(m_pendingStylesheets, 0);
 
     m_pendingStylesheets--;
     if (m_pendingStylesheets)
         return;
 
     document().didRemoveAllPendingStylesheet();
 }
 
@@ skipping 344 matching lines @@
     // Until import rules are supported in cached sheets it's not possible for loading to fail.
     DCHECK(!contents.didLoadErrorOccur());
     // It is not the original sheet anymore.
     if (contents.isMutable())
         return false;
     if (!contents.hasSyntacticallyValidCSSHeader())
         return false;
     return true;
 }
 
-CSSStyleSheet* StyleEngine::createSheet(Element* e, const String& text, TextPosition startPosition)
+CSSStyleSheet* StyleEngine::createSheet(Element* e, const String& text, TextPosition startPosition, bool isBeforeBody)
 {
     CSSStyleSheet* styleSheet = nullptr;
 
-    e->document().styleEngine().addPendingSheet();
+    e->document().styleEngine().addPendingSheet(isBeforeBody);
 
     AtomicString textContent(text);
 
     HeapHashMap<AtomicString, Member<StyleSheetContents>>::AddResult result = m_textToSheetCache.add(textContent, nullptr);
     if (result.isNewEntry || !result.storedValue->value) {
         styleSheet = StyleEngine::parseSheet(e, text, startPosition);
         if (result.isNewEntry && isCacheableForStyleElement(*styleSheet->contents())) {
             result.storedValue->value = styleSheet->contents();
             m_sheetToTextCache.add(styleSheet->contents(), textContent);
         }
@@ skipping 233 matching lines @@
     visitor->trace(m_styleInvalidator);
     visitor->trace(m_dirtyTreeScopes);
     visitor->trace(m_activeTreeScopes);
     visitor->trace(m_fontSelector);
     visitor->trace(m_textToSheetCache);
     visitor->trace(m_sheetToTextCache);
     CSSFontSelectorClient::trace(visitor);
 }
 
 } // namespace blink