Fix compilation of components_unittests with disable_file_support=true.

components/update_client/BUILD.gn

Index: components/update_client/BUILD.gn
diff --git a/components/update_client/BUILD.gn b/components/update_client/BUILD.gn
index 2833b159d8c530eedd1978cab72ededb72f8c0f3..69a82d87156aad3eb5e06d0ac5640368183cec84 100644
--- a/components/update_client/BUILD.gn
+++ b/components/update_client/BUILD.gn
@@ -2,6 +2,8 @@
 # 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",
@@ -115,7 +117,6 @@ 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",
@@ -126,6 +127,10 @@ source_set("unit_tests") {
     "utils_unittest.cc",
   ]
 
+  if (!disable_file_support) {
+    sources += [ "crx_downloader_unittest.cc" ]
+  }
+
   deps = [
     ":test_support",
     ":unit_tests_bundle_data",