Make CSSParserContext be garbage collected.

third_party/WebKit/Source/core/css/StyleSheetContents.cpp

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2006, 2007, 2012 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 41 matching lines @@
 
   for (unsigned i = 0; i < m_importRules.size(); ++i) {
     if (StyleSheetContents* sheet = m_importRules[i]->styleSheet())
       size += sheet->estimatedSizeInBytes();
   }
   return size;
 }
 
 StyleSheetContents::StyleSheetContents(StyleRuleImport* ownerRule,
                                        const String& originalURL,
-                                       const CSSParserContext& context)
+                                       const CSSParserContext* context)
     : m_ownerRule(ownerRule),
       m_originalURL(originalURL),
       m_defaultNamespace(starAtom),
       m_hasSyntacticallyValidCSSHeader(true),
       m_didLoadErrorOccur(false),
       m_isMutable(false),
       m_hasFontFaceRule(false),
       m_hasViewportRule(false),
       m_hasMediaQueries(false),
       m_hasSingleOwnerDocument(true),
@@ skipping 266 matching lines @@
   // remove this check. crbug.com/553535
   if (cachedStyleSheet->response().wasFetchedViaServiceWorker()) {
     const KURL originalURL(
         cachedStyleSheet->response().originalURLViaServiceWorker());
     // |originalURL| is empty when the response is created in the SW.
     if (!originalURL.isEmpty() && !securityOrigin->canRequest(originalURL))
       isSameOriginRequest = false;
   }
 
   CSSStyleSheetResource::MIMETypeCheck mimeTypeCheck =
-      isQuirksModeBehavior(m_parserContext.mode()) && isSameOriginRequest
+      isQuirksModeBehavior(m_parserContext->mode()) && isSameOriginRequest
           ? CSSStyleSheetResource::MIMETypeCheck::Lax
           : CSSStyleSheetResource::MIMETypeCheck::Strict;
   String sheetText = cachedStyleSheet->sheetText(mimeTypeCheck);
 
   const ResourceResponse& response = cachedStyleSheet->response();
   m_sourceMapURL = response.httpHeaderField(HTTPNames::SourceMap);
   if (m_sourceMapURL.isEmpty()) {
     // Try to get deprecated header.
     m_sourceMapURL = response.httpHeaderField(HTTPNames::X_SourceMap);
   }
 
-  CSSParserContext context(parserContext(), UseCounter::getFrom(this));
+  const CSSParserContext* context =
+      CSSParserContext::create(parserContext(), this);
   CSSParser::parseSheet(context, this, sheetText,
                         RuntimeEnabledFeatures::lazyParseCSSEnabled());
 
   DEFINE_STATIC_LOCAL(CustomCountHistogram, parseHistogram,
                       ("Style.AuthorStyleSheet.ParseTime", 0, 10000000, 50));
   double parseDurationSeconds = (monotonicallyIncreasingTime() - startTime);
   parseHistogram.count(parseDurationSeconds * 1000 * 1000);
   if (Document* document = singleOwnerDocument()) {
     CSSTiming::from(*document).recordAuthorStyleSheetParseTime(
         parseDurationSeconds);
   }
 }
 
 void StyleSheetContents::parseString(const String& sheetText) {
   parseStringAtPosition(sheetText, TextPosition::minimumPosition());
 }
 
 void StyleSheetContents::parseStringAtPosition(
     const String& sheetText,
     const TextPosition& startPosition) {
-  CSSParserContext context(parserContext(), UseCounter::getFrom(this));
+  const CSSParserContext* context =
+      CSSParserContext::create(parserContext(), this);
   CSSParser::parseSheet(context, this, sheetText);
 }
 
 bool StyleSheetContents::isLoading() const {
   for (unsigned i = 0; i < m_importRules.size(); ++i) {
     if (m_importRules[i]->isLoading())
       return true;
   }
   return false;
 }
@@ skipping 293 matching lines @@
 
 DEFINE_TRACE(StyleSheetContents) {
   visitor->trace(m_ownerRule);
   visitor->trace(m_importRules);
   visitor->trace(m_namespaceRules);
   visitor->trace(m_childRules);
   visitor->trace(m_loadingClients);
   visitor->trace(m_completedClients);
   visitor->trace(m_ruleSet);
   visitor->trace(m_referencedFromResource);
+  visitor->trace(m_parserContext);
 }
 
 }  // namespace blink