Allow chrome.debugger API to attach to extension background pages.

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 1103 matching lines @@
         'browser/extensions/api/autotest_private/autotest_private_apitest.cc',
         'browser/extensions/api/bluetooth/bluetooth_apitest.cc',
         'browser/extensions/api/bookmark_manager_private/bookmark_manager_private_apitest.cc',
         'browser/extensions/api/bookmarks/bookmark_apitest.cc',
         'browser/extensions/api/browsing_data/browsing_data_test.cc',
         'browser/extensions/api/cloud_print_private/cloud_print_private_apitest.cc',
         'browser/extensions/api/content_settings/content_settings_apitest.cc',
         'browser/extensions/api/context_menus/context_menu_apitest.cc',
         'browser/extensions/api/cookies/cookies_apitest.cc',
         'browser/extensions/api/debugger/debugger_apitest.cc',
+        'browser/extensions/api/debugger/debugger_extension_apitest.cc',
         'browser/extensions/api/declarative/declarative_apitest.cc',
         'browser/extensions/api/declarative_content/declarative_content_apitest.cc',
         'browser/extensions/api/developer_private/developer_private_apitest.cc',
         'browser/extensions/api/dial/dial_apitest.cc',
         'browser/extensions/api/dns/dns_apitest.cc',
         'browser/extensions/api/dns/mock_host_resolver_creator.cc',
         'browser/extensions/api/dns/mock_host_resolver_creator.h',
         'browser/extensions/api/downloads/downloads_api_unittest.cc',
         'browser/extensions/api/extension_action/browser_action_apitest.cc',
         'browser/extensions/api/extension_action/page_action_apitest.cc',
@@ skipping 2021 matching lines @@
               # more details.
               'DebugInformationFormat': '3',
               'ProgramDataBaseFileName': '<(PRODUCT_DIR)/browser_tests.exe.pdb',
             },
           },
         },
       ],
     }],
   ],  # 'conditions'
 }