Fix compilation of components_unittests with disable_file_support=true.

components/update_client/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("//net/features.gni")
+
 static_library("update_client") {
   sources = [
     "action.cc",
     "action.h",
     "action_update.cc",
     "action_update.h",
     "action_update_check.cc",
     "action_update_check.h",
     "action_wait.cc",
     "action_wait.h",
@@ skipping 93 matching lines @@
   outputs = [
     "{{bundle_resources_dir}}/" +
         "{{source_root_relative_dir}}/{{source_file_part}}",
   ]
 }
 
 source_set("unit_tests") {
   testonly = true
   sources = [
     "component_patcher_unittest.cc",
-    "crx_downloader_unittest.cc",
     "persisted_data_unittest.cc",
     "ping_manager_unittest.cc",
     "request_sender_unittest.cc",
     "update_checker_unittest.cc",
     "update_client_unittest.cc",
     "update_query_params_unittest.cc",
     "update_response_unittest.cc",
     "utils_unittest.cc",
   ]
 
+  if (!disable_file_support) {
+    sources += [ "crx_downloader_unittest.cc" ]
+  }
+
   deps = [
     ":test_support",
     ":unit_tests_bundle_data",
     ":update_client",
     "//base",
     "//components/prefs",
     "//components/prefs:test_support",
     "//courgette:courgette_lib",
     "//net:test_support",
     "//testing/gmock",
     "//testing/gtest",
     "//third_party/libxml",
   ]
 }