cros: Pass gaia_auth init params via postMessage.

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': {
     'chrome_browser_extensions_test_support_sources': [
       # A list of sources which is shared between different browser tests.
       'browser/apps/app_browsertest_util.cc',
       'browser/apps/app_browsertest_util.h',
       'browser/extensions/browsertest_util.cc',
@@ skipping 254 matching lines @@
       'browser/extensions/mutation_observers_apitest.cc',
       'browser/extensions/api/networking_config_chromeos_apitest_chromeos.cc',
       'browser/extensions/options_page_apitest.cc',
       'browser/extensions/page_action_browsertest.cc',
       'browser/extensions/plugin_apitest.cc',
       'browser/extensions/process_management_browsertest.cc',
       'browser/extensions/process_manager_browsertest.cc',
       'browser/extensions/requirements_checker_browsertest.cc',
       'browser/extensions/sandboxed_pages_apitest.cc',
       'browser/extensions/shared_module_apitest.cc',
+      'browser/extensions/signin/gaia_auth_extension_loader_browsertest.cc',
       'browser/extensions/startup_helper_browsertest.cc',
       'browser/extensions/stubs_apitest.cc',
       'browser/extensions/subscribe_page_action_browsertest.cc',
       'browser/extensions/web_contents_browsertest.cc',
       'browser/extensions/webstore_inline_installer_browsertest.cc',
       'browser/extensions/webstore_installer_browsertest.cc',
       'browser/extensions/webstore_installer_test.cc',
       'browser/extensions/webstore_installer_test.h',
       'browser/extensions/webstore_reinstaller_browsertest.cc',
       'browser/extensions/webstore_startup_installer_browsertest.cc',
@@ skipping 2946 matching lines @@
             ['enable_webrtc==1', {
               'dependencies': [
                 '../third_party/libjingle/libjingle.gyp:libjingle_webrtc'
               ]
             }],
           ],
         }]
     }],
   ],  # 'conditions'
 }