Fix null dereference on MemoryCache.

third_party/WebKit/Source/core/fetch/CSSStyleSheetResource.h

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller <mueller@kde.org>
     Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
     Copyright (C) 2004, 2005, 2006, 2007, 2008 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,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     Library General Public License for more details.
 
     You should have received a copy of the GNU Library General Public License
     along with this library; see the file COPYING.LIB.  If not, write to
     the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
     Boston, MA 02110-1301, USA.
 
     This class provides all functionality needed for loading images, style sheets and html
     pages from the web. It has a memory cache for these objects.
 */
 
 #ifndef CSSStyleSheetResource_h
 #define CSSStyleSheetResource_h
 
+#include "core/CoreExport.h"
 #include "core/fetch/ResourcePtr.h"
 #include "core/fetch/StyleSheetResource.h"
 #include "platform/heap/Handle.h"
 
 namespace blink {
 
 class CSSParserContext;
 class FetchRequest;
 class ResourceClient;
 class ResourceFetcher;
 class StyleSheetContents;
 
-class CSSStyleSheetResource final : public StyleSheetResource {
+class CORE_EXPORT CSSStyleSheetResource final : public StyleSheetResource {
 public:
     enum class MIMETypeCheck { Strict, Lax };
 
     static ResourcePtr<CSSStyleSheetResource> fetch(FetchRequest&, ResourceFetcher*);
+    static ResourcePtr<CSSStyleSheetResource> createForTest(const ResourceRequest&, const String& charset);
 
     ~CSSStyleSheetResource() override;
     DECLARE_VIRTUAL_TRACE();
 
     const String sheetText(MIMETypeCheck = MIMETypeCheck::Strict) const;
 
     const AtomicString mimeType() const;
 
     void didAddClient(ResourceClient*) override;
 
@@ skipping 25 matching lines @@
     String m_decodedSheetText;
 
     RefPtrWillBeMember<StyleSheetContents> m_parsedStyleSheetCache;
 };
 
 DEFINE_RESOURCE_TYPE_CASTS(CSSStyleSheet);
 
 }
 
 #endif