Remove BrowserSignin, as it's not used anywhere.

chrome/chrome_browser.gypi

 # Copyright (c) 2011 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.
 
 {
   'targets': [
     {
       'target_name': 'browser',
       'type': 'static_library',
       'dependencies': [
@@ skipping 282 matching lines @@
         'browser/browser_main_win.cc',
         'browser/browser_main_win.h',
         'browser/browser_process.cc',
         'browser/browser_process.h',
         'browser/browser_process_impl.cc',
         'browser/browser_process_impl.h',
         'browser/browser_process_sub_thread.cc',
         'browser/browser_process_sub_thread.h',
         'browser/browser_shutdown.cc',
         'browser/browser_shutdown.h',
-        'browser/browser_signin.cc',
-        'browser/browser_signin.h',
         'browser/browser_trial.cc',
         'browser/browser_trial.h',
         'browser/browser_util_win.cc',
         'browser/browser_util_win.h',
         'browser/browsing_data_appcache_helper.cc',
         'browser/browsing_data_appcache_helper.h',
         'browser/browsing_data_cookie_helper.cc',
         'browser/browsing_data_cookie_helper.h',
         'browser/browsing_data_database_helper.cc',
         'browser/browsing_data_database_helper.h',
@@ skipping 4560 matching lines @@
               # weak imports in dependents, who still must #include
               # closure_blocks_leopard_compat.h to get weak imports.
               'type': 'none',
             }],
           ],
         },
       ],
     }],
   ],
 }