Remove SharedBuffer::unlock() and keep Resource's SharedBuffer always locked

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

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller (mueller@kde.org)
     Copyright (C) 2002 Waldo Bastian (bastian@kde.org)
     Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
     Copyright (C) 2004, 2005, 2006 Apple Computer, Inc.
 
     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
@@ skipping 69 matching lines @@
     // because setCSSStyleSheet() may cause scripts to be executed, which could destroy 'c' if it is an instance of HTMLLinkElement.
     // see the comment of HTMLLinkElement::setCSSStyleSheet.
     Resource::didAddClient(c);
 
     if (!isLoading())
         static_cast<StyleSheetResourceClient*>(c)->setCSSStyleSheet(resourceRequest().url(), response().url(), encoding(), this);
 }
 
 const String CSSStyleSheetResource::sheetText(MIMETypeCheck mimeTypeCheck) const
 {
-    ASSERT(!isPurgeable());
-
     if (!data() || data()->isEmpty() || !canUseSheet(mimeTypeCheck))
         return String();
 
     if (!m_decodedSheetText.isNull())
         return m_decodedSheetText;
 
     // Don't cache the decoded text, regenerating is cheap and it can use quite a bit of memory
     return decodedText();
 }
 
@@ skipping 71 matching lines @@
         // This stylesheet resource did conflict with another resource and was
         // not added to the cache.
         setParsedStyleSheetCache(nullptr);
         return;
     }
     setParsedStyleSheetCache(sheet);
     setDecodedSize(m_parsedStyleSheetCache->estimatedSizeInBytes());
 }
 
 } // namespace blink