Refactor the way PaintArtifactCompositor is attached and used.

third_party/WebKit/Source/core/loader/EmptyClients.h

 /*
  * Copyright (C) 2006 Eric Seidel (eric@webkit.org)
  * Copyright (C) 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
  * Copyright (C) 2012 Samsung Electronics. 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
@@ skipping 141 matching lines @@
     ColorChooser* openColorChooser(LocalFrame*, ColorChooserClient*, const Color&) override;
     DateTimeChooser* openDateTimeChooser(DateTimeChooserClient*, const DateTimeChooserParameters&) override;
     void openTextDataListChooser(HTMLInputElement&) override;
 
     void openFileChooser(LocalFrame*, PassRefPtr<FileChooser>) override;
 
     void setCursor(const Cursor&, LocalFrame* localRoot) override {}
     Cursor lastSetCursorForTesting() const override { return pointerCursor(); }
 
     void attachRootGraphicsLayer(GraphicsLayer*, LocalFrame* localRoot) override {}
+    void attachRootLayer(WebLayer*, LocalFrame* localRoot) override {}
 
     void setEventListenerProperties(WebEventListenerClass, WebEventListenerProperties) override {}
     WebEventListenerProperties eventListenerProperties(WebEventListenerClass) const override { return WebEventListenerProperties::Nothing; }
     void setHasScrollEventHandlers(bool) override {}
     bool hasScrollEventHandlers() const override { return false; }
 
     void setTouchAction(TouchAction) override {}
 
     void didAssociateFormControlsAfterLoad(LocalFrame*) override {}
 
@@ skipping 158 matching lines @@
     ~EmptyContextMenuClient() override {}
     bool showContextMenu(const ContextMenu*, bool) override { return false; }
     void clearContextMenu() override {}
 };
 
 CORE_EXPORT void fillWithEmptyClients(Page::PageClients&);
 
 } // namespace blink
 
 #endif // EmptyClients_h