Support javascript gtests in an extension background page.

chrome/chrome_tests.gypi

 # Copyright 2013 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.
 {
   'includes': [
     'js_unittest_vars.gypi',
   ],
   'targets': [
     {
       'target_name': 'interactive_ui_tests',
@@ skipping 1523 matching lines @@
         'renderer/safe_browsing/phishing_dom_feature_extractor_browsertest.cc',
         'renderer/translate/translate_helper_browsertest.cc',
         'renderer/translate/translate_script_browsertest.cc',
         'test/base/browser_tests_main.cc',
         'test/base/chrome_render_view_test.cc',
         'test/base/chrome_render_view_test.h',
         'test/base/web_ui_browser_test.cc',
         'test/base/web_ui_browser_test.h',
         'test/base/web_ui_browser_test_browsertest.cc',
         'test/base/in_process_browser_test_browsertest.cc',
+        'test/base/javascript_browser_test.cc',
+        'test/base/javascript_browser_test.h',
         'test/base/tracing_browsertest.cc',
         'test/base/test_chrome_web_ui_controller_factory.cc',
         'test/base/test_chrome_web_ui_controller_factory.h',
         'test/base/test_chrome_web_ui_controller_factory_browsertest.cc',
         'test/data/chromeos/oobe_webui_browsertest.js',
         'test/data/pdf/pdf_extension_test.cc',
         'test/data/webui/about_invalidations_browsertest.js',
         'test/data/webui/accessibility_audit_browsertest.js',
         'test/data/webui/assertions.js',
         'test/data/webui/async_gen.cc',
@@ skipping 1401 matching lines @@
             ['enable_webrtc==1', {
               'dependencies': [
                 '../third_party/libjingle/libjingle.gyp:libjingle_webrtc'
               ]
             }],
           ],
         }]
     }],
   ],  # 'conditions'
 }