Add support for `width` based Width Client Hint

Source/core/html/HTMLImageElement.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2008, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Google 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.
  *
  */
 
 #ifndef HTMLImageElement_h
 #define HTMLImageElement_h
 
 #include "core/CoreExport.h"
+#include "core/fetch/FetchRequest.h"
 #include "core/html/HTMLElement.h"
 #include "core/html/HTMLImageLoader.h"
 #include "core/html/canvas/CanvasImageSource.h"
 #include "platform/graphics/GraphicsTypes.h"
 #include "platform/network/ResourceResponse.h"
 #include "wtf/WeakPtr.h"
 
 namespace blink {
 
 class HTMLFormElement;
@@ skipping 63 matching lines @@
     virtual FloatSize defaultDestinationSize() const override;
     virtual const KURL& sourceURL() const override;
     virtual bool isOpaque() const override;
 
     // public so that HTMLPictureElement can call this as well.
     void selectSourceURL(ImageLoader::UpdateFromElementBehavior);
     void reattachFallbackContent();
     void setUseFallbackContent();
     void setIsFallbackImage() { m_isFallbackImage = true; }
 
+    static int widthAttributeToInt(const String& value, bool& isValid);
+    FetchRequest::ResourceWidth resourceWidth();
     float sourceSize(Element&);
 
     void forceReload() const;
 
 protected:
     explicit HTMLImageElement(Document&, HTMLFormElement* = 0, bool createdByParser = false);
 
     virtual void didMoveToNewDocument(Document& oldDocument) override;
     virtual bool useFallbackContent() const { return m_useFallbackContent; }
 
@@ skipping 44 matching lines @@
     unsigned m_elementCreatedByParser : 1;
     // Intrinsic sizing is viewport dependant if the 'w' descriptor was used for the picked resource.
     unsigned m_intrinsicSizingViewportDependant : 1;
     unsigned m_useFallbackContent : 1;
     unsigned m_isFallbackImage : 1;
 };
 
 } // namespace blink
 
 #endif // HTMLImageElement_h