Move the test template to //testing/test.gni (part 2)

sandbox/mac/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("//build/config/mac/mac_sdk.gni")
+import("//testing/test.gni")
 
 component("sandbox") {
   sources = [
     "bootstrap_sandbox.cc",
     "bootstrap_sandbox.h",
     "dispatch_source_mach.cc",
     "dispatch_source_mach.h",
     "launchd_interception_server.cc",
     "launchd_interception_server.h",
     "mach_message_server.cc",
@@ skipping 77 matching lines @@
     "Foundation.framework",
   ]
 
   deps = [
     ":sandbox",
     "//base",
     "//base/test:run_all_unittests",
     "//testing/gtest",
   ]
 }