Support automatic javascript test registry in gtest when creating WebUI tests.

chrome/test/data/webui/sample_passing.js

+// 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.
+
+var helpers = {
+  helpAssertTrue: function(test) {
+    assertTrue(test);
+  },
+  helpAssertFalse: function(test) {
+    assertFalse(test);
+  }
+};
+
+// Sample tests that exercise the test JS library and show how this framework
+// could be used to test the downloads page.
+function testAssertFalse() {
+  assertFalse(false);
+}
+
+function testInitialFocus() {
+  assertTrue(document.activeElement.id == 'term', '');
+}
+
+function testHelpers() {
+  helpers.helpAssertTrue(true);
+  helpers.helpAssertFalse(false);
+}