[sf] Add support for transform hint in new front end

Bug: 238781169
Test: atest VulkanPreTransformTest --rerun-until-failure
Change-Id: Iececcce4101f1a8875ba20e2bfffad1775964ed1
diff --git a/services/surfaceflinger/FrontEnd/LayerSnapshot.h b/services/surfaceflinger/FrontEnd/LayerSnapshot.h
index e22c279..5491d9a 100644
--- a/services/surfaceflinger/FrontEnd/LayerSnapshot.h
+++ b/services/surfaceflinger/FrontEnd/LayerSnapshot.h
@@ -89,6 +89,7 @@
     gui::GameMode gameMode;
     scheduler::LayerInfo::FrameRate frameRate;
     ui::Transform::RotationFlags fixedTransformHint;
+    std::optional<ui::Transform::RotationFlags> transformHint;
     bool handleSkipScreenshotFlag = false;
     int32_t frameRateSelectionPriority;
     LayerHierarchy::TraversalPath mirrorRootPath;