Sync GN unit tests with GYP, add checking script.

chrome/test/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/chrome_build.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//chrome/chrome_tests.gni")
 import("//chrome/test/base/js2gtest.gni")
@@ skipping 559 matching lines @@
     if (!enable_app_list) {
       sources -= [ "../browser/ui/webui/app_list/start_page_browsertest.js" ]
     }
     if (!enable_supervised_users) {
       sources -=
           [ "../browser/ui/webui/downloads_ui_supervised_browsertest.js" ]
     }
     if (!enable_print_preview) {
       sources -= [ "data/webui/print_preview.js" ]
     }
+    if (enable_media_router) {
+      sources +=
+          [ "data/webui/media_router/media_router_elements_browsertest.js" ]
+    }
     deps = [
       "//chrome/browser/ui",
       "//skia",
     ]
     defines = [ "HAS_OUT_OF_PROC_TEST_RUNNER" ]
   }
 
   # TODO(GYP): Delete this after we've converted everything to GN.
   # The _run targets exist only for compatibility w/ GYP.
   group("tab_capture_end2end_tests_run") {
@@ skipping 1364 matching lines @@
     "//third_party/mojo/src/mojo/edk/system",
   ]
 
   if (!is_android && use_ash) {
     sources += rebase_path(
             chrome_tests_unit_gypi_values.chrome_test_support_unit_ash_sources,
             ".",
             "//chrome")
   }
 }