SF: Move frontend code to frontend namespace

Fixes: b/259553365
Test: presubmit
Change-Id: I47338ec3e8d151e09b3c22c0544ba948dc25b98d
diff --git a/services/surfaceflinger/FrontEnd/TransactionHandler.cpp b/services/surfaceflinger/FrontEnd/TransactionHandler.cpp
index 95961fe..8629671 100644
--- a/services/surfaceflinger/FrontEnd/TransactionHandler.cpp
+++ b/services/surfaceflinger/FrontEnd/TransactionHandler.cpp
@@ -24,7 +24,7 @@
 
 #include "TransactionHandler.h"
 
-namespace android {
+namespace android::surfaceflinger::frontend {
 
 void TransactionHandler::queueTransaction(TransactionState&& state) {
     mLocklessTransactionQueue.push(std::move(state));
@@ -186,4 +186,4 @@
         mStalledTransactions.erase(it);
     }
 }
-} // namespace android
+} // namespace android::surfaceflinger::frontend