Sync remaining components_unittests with GN

components/precache/core/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("//third_party/protobuf/proto_library.gni")
 
 # These values are duplicated in the GYP build in:
 # //components/precache/precache_defines.gypi
 precache_config_settings_url =
     "http://www.gstatic.com/chrome/wifiprefetch/precache_config"
@@ skipping 37 matching lines @@
   ]
 }
 
 source_set("unit_tests") {
   testonly = true
   sources = [
     "precache_database_unittest.cc",
     "precache_fetcher_unittest.cc",
     "precache_url_table_unittest.cc",
   ]
+
+  configs += [ ":precache_config" ]
+
   deps = [
     ":core",
     ":proto",
     "//testing/gmock",
     "//testing/gtest",
   ]
 }