Make it possible to include another file and port print_preview unit test to unit_tests.

chrome/test/data/unit/framework_unittest.gtestjs

+// Copyright (c) 2011 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.
+
+/**
+ * Class for testing the unit_test framework.
+ * @constructor
+ * @extends {testing.Test}
+ */
+function FrameworkUnitTest() {}
+
+FrameworkUnitTest.prototype = {
+  __proto__: testing.Test.prototype,
+};
+
+TEST_F('FrameworkUnitTest', 'ExpectTrueOk', function() {
+  expectTrue(true);
+});
+
+TEST_F('FrameworkUnitTest', 'AssertTrueOk', function() {
+  assertTrue(true);
+});
+
+/**
+ * Failing version of FrameworkUnitTest.
+ * @constructor
+ * @extends {FrameworkUnitTest}
+ */
+function FrameworkUnitTestFail() {}
+
+FrameworkUnitTestFail.prototype = {
+  __proto__: FrameworkUnitTest.prototype,
+
+  /** inheritDoc */
+  testShouldFail: true,
+};
+
+TEST_F('FrameworkUnitTestFail', 'ExpectFailFails', function() {
+  expectNotReached();
+});
+
+TEST_F('FrameworkUnitTestFail', 'AssertFailFails', function() {
+  assertNotReached();
+});