Remove dead code related to compositing from Sky

sky/engine/core/frame/SettingsDelegate.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 36 matching lines @@
     Settings* settings() const { return m_settings.get(); }
 
     // We currently use an enum instead of individual invalidation
     // functions to make generating Settings.in slightly easier.
     enum ChangeType {
         StyleChange,
         MediaTypeChange,
         MultisamplingChange,
         ImageLoadingChange,
         FontFamilyChange,
-        AcceleratedCompositingChange,
         MediaQueryChange,
     };
 
     virtual void settingsChanged(ChangeType) = 0;
 
 protected:
     OwnPtr<Settings> const m_settings;
 };
 
 } // namespace blink
 
 #endif  // SKY_ENGINE_CORE_FRAME_SETTINGSDELEGATE_H_