[sf] fix snapshot updates for mirror layers

Ensure we update the mirrored snapshots when they are
created.

Test: atest CtsSurfaceControlTests
Bug: 238781169

Change-Id: I245702f8b521745ba59f0f993bcaef90d0cdbe9a
diff --git a/services/surfaceflinger/FrontEnd/LayerSnapshot.h b/services/surfaceflinger/FrontEnd/LayerSnapshot.h
index 5d74203..9757640 100644
--- a/services/surfaceflinger/FrontEnd/LayerSnapshot.h
+++ b/services/surfaceflinger/FrontEnd/LayerSnapshot.h
@@ -84,6 +84,7 @@
     scheduler::LayerInfo::FrameRate frameRate;
     ui::Transform::RotationFlags fixedTransformHint;
     bool handleSkipScreenshotFlag = false;
+    LayerHierarchy::TraversalPath mirrorRootPath;
     ChildState childState;
 
     static bool isOpaqueFormat(PixelFormat format);