Migrate ITransactionCompletedListener to AIDL

This migrates the c++ interface to aidl.

Bug: 225250470
Test: atest libsurfaceflinger_unittest libgui_test SurfaceFlinger_test
Change-Id: I997e302ac8c6a23bedefaa5b8272677f3dce54df
diff --git a/services/surfaceflinger/FrontEnd/TransactionHandler.cpp b/services/surfaceflinger/FrontEnd/TransactionHandler.cpp
index 8629671..c2109b3 100644
--- a/services/surfaceflinger/FrontEnd/TransactionHandler.cpp
+++ b/services/surfaceflinger/FrontEnd/TransactionHandler.cpp
@@ -177,7 +177,7 @@
     }
 
     mStalledTransactions.push_back(transactionId);
-    listener->onTransactionQueueStalled(String8(reason.c_str()));
+    listener->onTransactionQueueStalled(reason);
 }
 
 void TransactionHandler::removeFromStalledTransactions(uint64_t id) {