Allow write_fmt to work on &OutFile
diff --git a/gen/mod.rs b/gen/mod.rs
index 8006898..523ba1d 100644
--- a/gen/mod.rs
+++ b/gen/mod.rs
@@ -9,7 +9,6 @@
 
 use self::error::format_err;
 use self::namespace::Namespace;
-use self::out::OutFile;
 use crate::syntax::{self, check, ident, Types};
 use quote::quote;
 use std::fs;
@@ -44,17 +43,17 @@
     pub include: Vec<String>,
 }
 
-pub(super) fn do_generate_bridge(path: &Path, opt: Opt) -> OutFile {
+pub(super) fn do_generate_bridge(path: &Path, opt: Opt) -> Vec<u8> {
     let header = false;
     generate(path, opt, header)
 }
 
-pub(super) fn do_generate_header(path: &Path, opt: Opt) -> OutFile {
+pub(super) fn do_generate_header(path: &Path, opt: Opt) -> Vec<u8> {
     let header = true;
     generate(path, opt, header)
 }
 
-fn generate(path: &Path, opt: Opt, header: bool) -> OutFile {
+fn generate(path: &Path, opt: Opt, header: bool) -> Vec<u8> {
     let source = match fs::read_to_string(path) {
         Ok(source) => source,
         Err(err) => format_err(path, "", Error::Io(err)),
@@ -68,7 +67,7 @@
         let out = write::gen(bridge.namespace, &apis, &types, opt, header);
         Ok(out)
     })() {
-        Ok(out) => out,
+        Ok(out) => out.content(),
         Err(err) => format_err(path, &source, err),
     }
 }