Add a function to send scripts from a browsertest to an extension's 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.
 {
   'variables' : {
     'pyautolib_sources': [
       'app/chrome_command_ids.h',
       'app/chrome_dll_resource.h',
       'common/automation_constants.h',
       'common/pref_names.cc',
@@ skipping 1386 matching lines @@
         'browser/extensions/docs/examples/apps/calculator_browsertest.cc',
         'browser/extensions/error_console/error_console_browsertest.cc',
         'browser/extensions/events_apitest.cc',
         'browser/extensions/execute_script_apitest.cc',
         'browser/extensions/extension_apitest.cc',
         'browser/extensions/extension_apitest.h',
         'browser/extensions/extension_bindings_apitest.cc',
         'browser/extensions/extension_blacklist_browsertest.cc',
         'browser/extensions/extension_browsertest.cc',
         'browser/extensions/extension_browsertest.h',
+        'browser/extensions/extension_browsertest_util.cc',
+        'browser/extensions/extension_browsertest_util.h',
+        'browser/extensions/extension_browsertest_util_browsertest.cc',
         'browser/extensions/extension_context_menu_browsertest.cc',
         'browser/extensions/extension_disabled_ui_browsertest.cc',
         'browser/extensions/extension_dom_clipboard_apitest.cc',
         'browser/extensions/extension_fileapi_apitest.cc',
         'browser/extensions/extension_functional_browsertest.cc',
         'browser/extensions/extension_function_test_utils.cc',
         'browser/extensions/extension_function_test_utils.h',
         'browser/extensions/extension_geolocation_apitest.cc',
         'browser/extensions/extension_get_views_apitest.cc',
         'browser/extensions/extension_icon_source_apitest.cc',
@@ skipping 2056 matching lines @@
             'utility',
           ],
           'sources': [
             'tools/service_discovery_sniffer/service_discovery_sniffer.h',
             'tools/service_discovery_sniffer/service_discovery_sniffer.cc',
           ],
         }]
     }],
   ],  # 'conditions'
 }