DevTools: migrate inspector's ParsedStyleSheet to Oilpan.

Source/core/inspector/InspectorStyleSheet.h

 /*
  * Copyright (C) 2010, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
@@ skipping 224 matching lines @@
     bool startsAtZero() const;
 
     void updateText(const String& newText);
     Element* ownerStyleElement() const;
 
     RawPtrWillBeMember<InspectorCSSAgent> m_cssAgent;
     RawPtrWillBeMember<InspectorResourceAgent> m_resourceAgent;
     RefPtrWillBeMember<CSSStyleSheet> m_pageStyleSheet;
     TypeBuilder::CSS::StyleSheetOrigin::Enum m_origin;
     String m_documentURL;
-    OwnPtr<ParsedStyleSheet> m_parsedStyleSheet;
+    OwnPtrWillBeMember<ParsedStyleSheet> m_parsedStyleSheet;
     mutable CSSRuleVector m_flatRules;
     mutable String m_sourceURL;
 };
 
 class InspectorStyleSheetForInlineStyle final : public InspectorStyleSheetBase {
 public:
     static PassRefPtrWillBeRawPtr<InspectorStyleSheetForInlineStyle> create(const String& id, PassRefPtrWillBeRawPtr<Element>, Listener*);
 
     void didModifyElementAttribute();
     virtual Document* ownerDocument() const override;
@@ skipping 28 matching lines @@
     mutable String m_styleText;
     mutable bool m_isStyleTextValid;
 };
 
 
 } // namespace blink
 
 WTF_ALLOW_MOVE_AND_INIT_WITH_MEM_FUNCTIONS(blink::InspectorStyleProperty);
 
 #endif // !defined(InspectorStyleSheet_h)