If a compositing update is declared as needed, scheduleAnimation should be triggered.

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 115 matching lines @@
 
     virtual bool tabsToLinks() OVERRIDE { return false; }
 
     virtual IntRect windowResizerRect() const OVERRIDE { return IntRect(); }
 
     virtual void invalidateContentsAndRootView(const IntRect&) OVERRIDE { }
     virtual void invalidateContentsForSlowScroll(const IntRect&) OVERRIDE { }
     virtual void scroll(const IntSize&, const IntRect&, const IntRect&) OVERRIDE { }
     virtual void scheduleAnimation() OVERRIDE { }
 
+    virtual bool isCompositorFramePending() const OVERRIDE { return false; }
+
     virtual IntRect rootViewToScreen(const IntRect& r) const OVERRIDE { return r; }
     virtual blink::WebScreenInfo screenInfo() const OVERRIDE { return blink::WebScreenInfo(); }
     virtual void contentsSizeChanged(Frame*, const IntSize&) const OVERRIDE { }
 
     virtual void mouseDidMoveOverElement(const HitTestResult&, unsigned) OVERRIDE { }
 
     virtual void setToolTip(const String&, TextDirection) OVERRIDE { }
 
     virtual void print(Frame*) OVERRIDE { }
 
@@ skipping 181 matching lines @@
 public:
     virtual PassOwnPtr<StorageNamespace> createSessionStorageNamespace() OVERRIDE;
     virtual bool canAccessStorage(Frame*, StorageType) const OVERRIDE { return false; }
 };
 
 void fillWithEmptyClients(Page::PageClients&);
 
 }
 
 #endif // EmptyClients_h