SF: Refactor onLayerDisplayed

Adds a new LayerFE::onLayerDisplayed interface, and adjusts the
front-end Layer to match.

Adjusts the code in SurfaceFlinger to use the new interface, in
preparation to moving the loop over to CompositionEngine.

Test: atest libsurfaceflinger_unittest libcompositionengine_test
Bug: 121291683
Change-Id: I9231f4b425ea1b9f37363521c7e3f6aef63bcec6
diff --git a/services/surfaceflinger/CompositionEngine/include/compositionengine/mock/LayerFE.h b/services/surfaceflinger/CompositionEngine/include/compositionengine/mock/LayerFE.h
index 92e0070..a0c2a63 100644
--- a/services/surfaceflinger/CompositionEngine/include/compositionengine/mock/LayerFE.h
+++ b/services/surfaceflinger/CompositionEngine/include/compositionengine/mock/LayerFE.h
@@ -18,6 +18,7 @@
 
 #include <compositionengine/LayerFE.h>
 #include <gmock/gmock.h>
+#include <ui/Fence.h>
 
 namespace android::compositionengine::mock {
 
@@ -27,6 +28,8 @@
 public:
     LayerFE();
     virtual ~LayerFE();
+
+    MOCK_METHOD1(onLayerDisplayed, void(const sp<Fence>&));
 };
 
 } // namespace android::compositionengine::mock