--- a/gfx/layers/composite/AsyncCompositionManager.h
+++ b/gfx/layers/composite/AsyncCompositionManager.h
@@ -7,16 +7,17 @@
 #define GFX_ASYNCCOMPOSITIONMANAGER_H
 
 #include "gfxPoint.h"
 #include "gfx3DMatrix.h"
 #include "nsAutoPtr.h"
 #include "nsRect.h"
 #include "mozilla/dom/ScreenOrientation.h"
 #include "mozilla/gfx/Rect.h"
+#include "mozilla/Attributes.h"
 #include "mozilla/RefPtr.h"
 #include "mozilla/TimeStamp.h"
 #include "mozilla/layers/LayerTransaction.h" // for TargetConfig
 
 namespace mozilla {
 namespace layers {
 
 class AsyncPanZoomController;
@@ -46,17 +47,17 @@ struct ViewTransform {
 /**
  * Manage async composition effects. This class is only used with OMTC and only
  * lives on the compositor thread. It is a layer on top of the layer manager
  * (LayerManagerComposite) which deals with elements of composition which are
  * usually dealt with by dom or layout when main thread rendering, but which can
  * short circuit that stuff to directly affect layers as they are composited,
  * for example, off-main thread animation, async video, async pan/zoom.
  */
-class AsyncCompositionManager : public RefCounted<AsyncCompositionManager>
+class AsyncCompositionManager MOZ_FINAL : public RefCounted<AsyncCompositionManager>
 {
   friend class AutoResolveRefLayers;
 public:
   AsyncCompositionManager(LayerManagerComposite* aManager)
     : mXScale(1.0)
     , mYScale(1.0)
     , mLayerManager(aManager)
     , mIsFirstPaint(false)