mandoline: write this after lunch.

components/filesystem/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//mojo/public/mojo_application.gni")
 
 source_set("lib") {
   sources = [
     "directory_impl.cc",
     "directory_impl.h",
     "file_impl.cc",
     "file_impl.h",
     "file_system_app.cc",
     "file_system_app.h",
     "file_system_impl.cc",
     "file_system_impl.h",
     "util.cc",
     "util.h",
   ]
 
   deps = [
     "//base",
     "//components/filesystem/public/interfaces",
     "//mojo/application/public/cpp",
     "//mojo/common",
     "//mojo/common:common_base",
     "//mojo/platform_handle",
+    "//mojo/services/tracing/public/cpp",
     "//url",
   ]
 }
 
 mojo_native_application("filesystem") {
   sources = [
     "main.cc",
   ]
 
   deps = [
@@ skipping 25 matching lines @@
     "//components/filesystem/public/interfaces",
     "//mojo/application/public/cpp:test_support",
     "//mojo/platform_handle:for_shared_library",
     "//mojo/public/cpp/bindings",
   ]
 
   data_deps = [
     ":filesystem",
   ]
 }