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

third_party/WebKit/Source/core/fetch/ImageResource.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 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.
@@ skipping 149 matching lines @@
     // If not null, changeRect is the changed part of the image.
     void notifyObservers(const IntRect* changeRect = nullptr);
 
     void ensureImage();
 
     void checkNotify() override;
     void markClientsAndObserversFinished() override;
 
     void doResetAnimation();
 
-    bool isSafeToUnlock() const override;
     void destroyDecodedDataIfPossible() override;
     void destroyDecodedDataForFailedRevalidation() override;
 
     float m_devicePixelRatioHeaderValue;
 
     Member<MultipartImageResourceParser> m_multipartParser;
     RefPtr<blink::Image> m_image;
     MultipartParsingState m_multipartParsingState = MultipartParsingState::WaitingForFirstPart;
     bool m_hasDevicePixelRatioHeaderValue;
     HashCountedSet<ImageResourceObserver*> m_observers;
     HashCountedSet<ImageResourceObserver*> m_finishedObservers;
 };
 
 DEFINE_RESOURCE_TYPE_CASTS(Image);
 
 } // namespace blink
 
 #endif