0 -> nullptr for UseCounter pointer in CSSParserContext.

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
@@ skipping 45 matching lines @@
 }
 
 static const MediaQueryEvaluator& printEval()
 {
     DEFINE_STATIC_LOCAL(MediaQueryEvaluator, staticPrintEval, (new MediaQueryEvaluator("print")));
     return staticPrintEval;
 }
 
 static StyleSheetContents* parseUASheet(const String& str)
 {
-    StyleSheetContents* sheet = StyleSheetContents::create(CSSParserContext(UASheetMode, 0));
+    StyleSheetContents* sheet = StyleSheetContents::create(CSSParserContext(UASheetMode, nullptr));
     sheet->parseString(str);
     // User Agent stylesheets are parsed once for the lifetime of the renderer
     // process and are intentionally leaked.
     LEAK_SANITIZER_IGNORE_OBJECT(sheet);
     return sheet;
 }
 
 CSSDefaultStyleSheets::CSSDefaultStyleSheets()
     : m_defaultStyle(nullptr)
     , m_defaultMobileViewportStyle(nullptr)
@@ skipping 128 matching lines @@
     visitor->trace(m_mobileViewportStyleSheet);
     visitor->trace(m_televisionViewportStyleSheet);
     visitor->trace(m_quirksStyleSheet);
     visitor->trace(m_svgStyleSheet);
     visitor->trace(m_mathmlStyleSheet);
     visitor->trace(m_mediaControlsStyleSheet);
     visitor->trace(m_fullscreenStyleSheet);
 }
 
 } // namespace blink