Have srcset respond to viewport changes

Source/core/dom/Document.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
@@ skipping 131 matching lines @@
 class StyleResolver;
 class StyleSheet;
 class StyleSheetList;
 class Text;
 class TextAutosizer;
 class Touch;
 class TouchList;
 class TransformSource;
 class TreeWalker;
 class VisitedLinkState;
+class ViewportChangeNotifier;
 class WebGLRenderingContext;
 
 struct AnnotatedRegionValue;
 struct IconURL;
 
 typedef EventWithHitTestResults<PlatformMouseEvent> MouseEventWithHitTestResults;
 typedef int ExceptionCode;
 
 enum StyleResolverUpdateMode {
     // Discards the StyleResolver and rebuilds it.
@@ skipping 864 matching lines @@
     void registerVisibilityObserver(DocumentVisibilityObserver*);
     void unregisterVisibilityObserver(DocumentVisibilityObserver*);
 
     void updateStyleInvalidationIfNeeded();
 
     virtual void trace(Visitor*) OVERRIDE;
 
     bool hasSVGFilterElementsRequiringLayerUpdate() const { return m_layerUpdateSVGFilterElements.size(); }
     void didRecalculateStyleForElement() { ++m_styleRecalcElementCounter; }
 
+    ViewportChangeNotifier& viewportChangeNotifier() { return *m_viewportChangeNotifier; }
+
 protected:
     Document(const DocumentInit&, DocumentClassFlags = DefaultDocumentClass);
 
     virtual void didUpdateSecurityOrigin() OVERRIDE FINAL;
 
     void clearXMLVersion() { m_xmlVersion = String(); }
 
 #if !ENABLE(OILPAN)
     virtual void dispose() OVERRIDE;
 #endif
@@ skipping 272 matching lines @@
     ViewportDescription m_legacyViewportDescription;
     Length m_viewportDefaultMinWidth;
 
     bool m_didSetReferrerPolicy;
     ReferrerPolicy m_referrerPolicy;
 
     bool m_directionSetOnDocumentElement;
     bool m_writingModeSetOnDocumentElement;
     DocumentTiming m_documentTiming;
     RefPtrWillBeMember<MediaQueryMatcher> m_mediaQueryMatcher;
+    OwnPtrWillBeMember<ViewportChangeNotifier> m_viewportChangeNotifier;
     bool m_writeRecursionIsTooDeep;
     unsigned m_writeRecursionDepth;
 
     RefPtrWillBeMember<ScriptedAnimationController> m_scriptedAnimationController;
     OwnPtr<MainThreadTaskRunner> m_taskRunner;
     OwnPtr<TextAutosizer> m_textAutosizer;
     OwnPtr<FastTextAutosizer> m_fastTextAutosizer;
 
     RefPtrWillBeMember<CustomElementRegistrationContext> m_registrationContext;
     RefPtrWillBeMember<CustomElementMicrotaskRunQueue> m_customElementMicrotaskRunQueue;
@@ skipping 71 matching lines @@
 Node* eventTargetNodeForDocument(Document*);
 
 } // namespace WebCore
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showLiveDocumentInstances();
 #endif
 
 #endif // Document_h