Add missing grpc_slice_unref to bm_metadata
diff --git a/test/cpp/microbenchmarks/bm_metadata.cc b/test/cpp/microbenchmarks/bm_metadata.cc
index d6ccee5..eeba309 100644
--- a/test/cpp/microbenchmarks/bm_metadata.cc
+++ b/test/cpp/microbenchmarks/bm_metadata.cc
@@ -63,6 +63,7 @@
   for (auto _ : state) {
     grpc_slice_unref(grpc_core::ManagedMemorySlice(&slice));
   }
+  grpc_slice_unref(slice);
   track_counters.Finish(state);
 }
 BENCHMARK(BM_SliceReIntern);