Fence on draws that are reported

Change-Id: Ib2ec16cbda40f40df1710bdc868869ea8301f17e
diff --git a/libs/hwui/renderthread/RenderProxy.h b/libs/hwui/renderthread/RenderProxy.h
index f1ca534..fc51d21 100644
--- a/libs/hwui/renderthread/RenderProxy.h
+++ b/libs/hwui/renderthread/RenderProxy.h
@@ -78,6 +78,8 @@
     ANDROID_API bool copyLayerInto(DeferredLayerUpdater* layer, SkBitmap* bitmap);
     ANDROID_API void destroyLayer(DeferredLayerUpdater* layer);
 
+    ANDROID_API void fence();
+
 private:
     RenderThread& mRenderThread;
     CanvasContext* mContext;