Files TS: Convert the test_util.js to TS

Bug: b:319189127
Change-Id: Ic226c0f8d6673eaaa2eb40154c13e614085d4533
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5294614
Reviewed-by: Ben Reich <[email protected]>
Commit-Queue: Ben Reich <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1260753}
diff --git a/ui/file_manager/integration_tests/BUILD.gn b/ui/file_manager/integration_tests/BUILD.gn
index c48e7a6..bda63d59 100644
--- a/ui/file_manager/integration_tests/BUILD.gn
+++ b/ui/file_manager/integration_tests/BUILD.gn
@@ -8,7 +8,7 @@
 tsc_folder = "$target_gen_dir/tsc"
 
 js_files = [
-  "test_util.js",
+  "test_util.ts",
 
   # File Manager.
   "file_manager/background.js",