--- a/gfx/layers/composite/LayerManagerComposite.cpp
+++ b/gfx/layers/composite/LayerManagerComposite.cpp
@@ -198,16 +198,17 @@ LayerManagerComposite::EndEmptyTransacti
 }
 
 void
 LayerManagerComposite::EndTransaction(DrawThebesLayerCallback aCallback,
                                       void* aCallbackData,
                                       EndTransactionFlags aFlags)
 {
   NS_ASSERTION(mInTransaction, "Didn't call BeginTransaction?");
+  NS_ASSERTION(!aCallback && !aCallbackData, "Not expecting callbacks here");
   mInTransaction = false;
 
   if (!mIsCompositorReady) {
     return;
   }
   mIsCompositorReady = false;
 
 #ifdef MOZ_LAYERS_HAVE_LOG
@@ -235,23 +236,17 @@ LayerManagerComposite::EndTransaction(Dr
       // properties.
       mRoot->ApplyPendingUpdatesToSubtree();
     }
 
     // The results of our drawing always go directly into a pixel buffer,
     // so we don't need to pass any global transform here.
     mRoot->ComputeEffectiveTransforms(gfx3DMatrix());
 
-    mThebesLayerCallback = aCallback;
-    mThebesLayerCallbackData = aCallbackData;
-
     Render();
-
-    mThebesLayerCallback = nullptr;
-    mThebesLayerCallbackData = nullptr;
   }
 
   mCompositor->SetTargetContext(nullptr);
 
 #ifdef MOZ_LAYERS_HAVE_LOG
   Log();
   MOZ_LAYERS_LOG(("]----- EndTransaction"));
 #endif

--- a/gfx/layers/composite/LayerManagerComposite.h
+++ b/gfx/layers/composite/LayerManagerComposite.h
@@ -148,22 +148,16 @@ public:
   {
     MOZ_CRASH("Shouldn't be called for composited layer manager");
   }
 
   virtual already_AddRefed<gfxASurface>
     CreateOptimalMaskSurface(const gfxIntSize &aSize) MOZ_OVERRIDE;
 
 
-  DrawThebesLayerCallback GetThebesLayerCallback() const
-  { return mThebesLayerCallback; }
-
-  void* GetThebesLayerCallbackData() const
-  { return mThebesLayerCallbackData; }
-
   virtual const char* Name() const MOZ_OVERRIDE { return ""; }
 
   enum WorldTransforPolicy {
     ApplyWorldTransform,
     DontApplyWorldTransform
   };
 
   /**
@@ -266,20 +260,16 @@ private:
 
   void WorldTransformRect(nsIntRect& aRect);
 
   RefPtr<Compositor> mCompositor;
 
   /** Our more efficient but less powerful alter ego, if one is available. */
   nsRefPtr<Composer2D> mComposer2D;
 
-  /* Thebes layer callbacks; valid at the end of a transaciton,
-   * while rendering */
-  DrawThebesLayerCallback mThebesLayerCallback;
-  void *mThebesLayerCallbackData;
   gfxMatrix mWorldMatrix;
 
   bool mInTransaction;
   bool mIsCompositorReady;
   nsIntRegion mInvalidRegion;
   nsAutoPtr<LayerProperties> mClonedLayerTreeProperties;
   bool mDebugOverlayWantsNextFrame;
 };