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

mojo/services/html_viewer/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("//testing/test.gni")
 import("//third_party/mojo/src/mojo/public/mojo.gni")
 import("//third_party/mojo/src/mojo/public/mojo_application.gni")
 
 action("generate_blink_resource_map") {
   script = "//mojo/services/html_viewer/generate_blink_resource_map.py"
   args = [
     "--pak-file",
     rebase_path("$root_out_dir/gen/blink/public/resources/blink_resources.pak"),
     "--header",
     rebase_path("$target_gen_dir/blink_resource_map.h"),
@@ skipping 104 matching lines @@
 test("tests") {
   output_name = "html_viewer_unittests"
   sources = [
     "ax_provider_impl_unittest.cc",
   ]
   deps = [
     ":lib",
     "//base/test:run_all_unittests",
   ]
 }