SF: Move frontend code to frontend namespace

Fixes: b/259553365
Test: presubmit
Change-Id: I47338ec3e8d151e09b3c22c0544ba948dc25b98d
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 2c510d7..fad951e 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -180,6 +180,7 @@
 using base::StringAppendF;
 using display::PhysicalDisplay;
 using display::PhysicalDisplays;
+using frontend::TransactionHandler;
 using gui::DisplayInfo;
 using gui::GameMode;
 using gui::IDisplayEventConnection;
@@ -3304,7 +3305,7 @@
         if (!layer->needsInputInfo()) return;
 
         const auto opt = mFrontEndDisplayInfos.get(layer->getLayerStack())
-                                 .transform([](const FrontEndDisplayInfo& info) {
+                                 .transform([](const frontend::DisplayInfo& info) {
                                      return Layer::InputDisplayArgs{&info.transform, info.isSecure};
                                  });