Fix inline/refcounted slice problem in gzip
diff --git a/src/core/lib/compression/stream_compression_gzip.cc b/src/core/lib/compression/stream_compression_gzip.cc
index 9d829b3..897f391 100644
--- a/src/core/lib/compression/stream_compression_gzip.cc
+++ b/src/core/lib/compression/stream_compression_gzip.cc
@@ -114,7 +114,8 @@
     if (ctx->zs.avail_out == 0) {
       grpc_slice_buffer_add(out, slice_out);
     } else if (ctx->zs.avail_out < slice_size) {
-      slice_out.data.refcounted.length -= ctx->zs.avail_out;
+      size_t len = GRPC_SLICE_LENGTH(slice_out);
+      GRPC_SLICE_SET_LENGTH(slice_out, len - ctx->zs.avail_out);
       grpc_slice_buffer_add(out, slice_out);
     } else {
       grpc_slice_unref_internal(slice_out);