binder: Add FD support to RPC Binder

Bug: 185909244
Test: TH
Change-Id: Ic4fc1b1edfe9d69984e785553cd1aaca97a07da3
diff --git a/libs/binder/tests/IBinderRpcTest.aidl b/libs/binder/tests/IBinderRpcTest.aidl
index 2deea82..b15a225 100644
--- a/libs/binder/tests/IBinderRpcTest.aidl
+++ b/libs/binder/tests/IBinderRpcTest.aidl
@@ -67,4 +67,8 @@
     void scheduleShutdown();
 
     void useKernelBinderCallingId();
+
+    ParcelFileDescriptor echoAsFile(@utf8InCpp String content);
+
+    ParcelFileDescriptor concatFiles(in List<ParcelFileDescriptor> files);
 }