Use ScopedTaskEnvironment instead of MessageLoop in tests that use v8.

gin/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("//v8/gni/v8.gni")
 
 # This is depended upon from the browser DLL on Windows, where V8 is not used,
 # but features are enabled. This cannot depend on V8.
 component("gin_features") {
@@ skipping 135 matching lines @@
   ]
   data = [
     "test/expect.js",
   ]
 
   public_deps = [
     ":gin",
     "//testing/gtest",
   ]
   deps = [
+    "//base/test:test_support",
     "//v8",
   ]
 
   configs += [ "//v8:external_startup_data" ]
 }
 
 test("gin_unittests") {
   sources = [
     "arguments_unittest.cc",
     "converter_unittest.cc",
@@ skipping 25 matching lines @@
     "shell/hello_world.js",
     "test/file_unittests.js",
     "test/gtest_unittests.js",
     "../OWNERS",
   ]
 
   data_deps = [
     ":gin_shell",
   ]
 }