diff --git a/services/surfaceflinger/DisplayDevice.h b/services/surfaceflinger/DisplayDevice.h
index bf249cd..130ad1f 100644
--- a/services/surfaceflinger/DisplayDevice.h
+++ b/services/surfaceflinger/DisplayDevice.h
@@ -285,4 +285,16 @@
     DisplayModes supportedModes;
 };
 
+// Predicates for display lookup.
+
+struct WithLayerStack {
+    explicit WithLayerStack(ui::LayerStack layerStack) : layerStack(layerStack) {}
+
+    bool operator()(const DisplayDevice& display) const {
+        return display.getLayerStack() == layerStack;
+    }
+
+    ui::LayerStack layerStack;
+};
+
 } // namespace android