Add a method to LoginUIService to open the sign in UI in a popup.

chrome/chrome_tests.gypi

 # Copyright (c) 2012 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 1820 matching lines @@
         'browser/ui/views/tabs/tab_strip_unittest.cc',
         'browser/ui/views/tabs/touch_tab_strip_layout_unittest.cc',
         'browser/ui/website_settings/website_settings_unittest.cc',
         'browser/ui/webui/chrome_web_ui_data_source_unittest.cc',
         'browser/ui/webui/fileicon_source_unittest.cc',
         'browser/ui/webui/ntp/suggestions_combiner_unittest.cc',
         'browser/ui/webui/options2/language_options_handler2_unittest.cc',
         'browser/ui/webui/policy_ui_unittest.cc',
         'browser/ui/webui/print_preview/print_preview_handler_unittest.cc',
         'browser/ui/webui/print_preview/print_preview_ui_unittest.cc',
+        'browser/ui/webui/signin/login_ui_service_unittest.cc',
         'browser/ui/webui/sync_internals_ui_unittest.cc',
         'browser/ui/webui/sync_setup_handler_unittest.cc',
         'browser/ui/webui/theme_source_unittest.cc',
         'browser/ui/webui/web_dialog_web_contents_delegate_unittest.cc',
         'browser/ui/webui/web_ui_unittest.cc',
         'browser/ui/window_sizer/window_sizer_ash_unittest.cc',
         'browser/ui/window_sizer/window_sizer_unittest.cc',
         'browser/ui/window_snapshot/window_snapshot_mac_unittest.mm',
         'browser/chrome_to_mobile_service_unittest.cc',
         'browser/user_style_sheet_watcher_unittest.cc',
@@ skipping 2826 matching lines @@
               # Use outputs of this action as inputs for the main target build.
               # Seems as a misnomer but makes this happy on Linux (scons).
               'process_outputs_as_sources': 1,
             },
           ],  # 'actions'
         },
       ]
     }],  # 'coverage!=0'
   ],  # 'conditions'
 }