Add benchmark for sending a vector of binders over AIDL

Test: atest libbinder_benchmark
Bug: none
Change-Id: I94ed998dda092e581884167d845d2c0d8b419ee3
diff --git a/tests/libhwbinder/aidl/android/tests/binder/IBenchmark.aidl b/tests/libhwbinder/aidl/android/tests/binder/IBenchmark.aidl
index be91fb9..bc44e95 100644
--- a/tests/libhwbinder/aidl/android/tests/binder/IBenchmark.aidl
+++ b/tests/libhwbinder/aidl/android/tests/binder/IBenchmark.aidl
@@ -1,5 +1,6 @@
 package android.tests.binder;
 
 interface IBenchmark {
-  byte[] sendVec(in byte[] data);
-}
\ No newline at end of file
+    byte[] sendVec(in byte[] data);
+    IBinder[] sendBinderVec(in IBinder[] data);
+}