diff --git a/libs/hwui/DisplayList.h b/libs/hwui/DisplayList.h
index cab092f..ef0fd31 100644
--- a/libs/hwui/DisplayList.h
+++ b/libs/hwui/DisplayList.h
@@ -125,8 +125,8 @@
 
     virtual void syncContents();
     virtual void updateChildren(std::function<void(RenderNode*)> updateFn);
-    virtual bool prepareListAndChildren(TreeInfo& info, bool functorsNeedLayer,
-            std::function<void(RenderNode*, TreeInfo&, bool)> childFn);
+    virtual bool prepareListAndChildren(TreeObserver& observer, TreeInfo& info, bool functorsNeedLayer,
+            std::function<void(RenderNode*, TreeObserver&, TreeInfo&, bool)> childFn);
 
 protected:
     // allocator into which all ops and LsaVector arrays allocated