Start implementing an auth flow for platform apps to be able to do auth

chrome/chrome_browser_extensions.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.
 
 {
   'targets': [
     {
       'target_name': 'browser_extensions',
       'type': 'static_library',
       'variables': { 'enable_wexit_time_destructors': 1, },
@@ skipping 96 matching lines @@
         'browser/extensions/api/declarative_webrequest/webrequest_rules_registry.h',
         'browser/extensions/api/dns/dns_api.cc',
         'browser/extensions/api/dns/dns_api.h',
         'browser/extensions/api/extension_action/extension_actions_api.cc',
         'browser/extensions/api/extension_action/extension_actions_api.h',
         'browser/extensions/api/extension_action/extension_browser_actions_api.h',
         'browser/extensions/api/extension_action/extension_page_actions_api.cc',
         'browser/extensions/api/extension_action/extension_page_actions_api.h',
         'browser/extensions/api/extension_action/extension_page_actions_api_constants.cc',
         'browser/extensions/api/extension_action/extension_page_actions_api_constants.h',
+        'browser/extensions/api/identity/extension_auth_flow.cc',
+        'browser/extensions/api/identity/extension_auth_flow.h',
         'browser/extensions/api/identity/identity_api.cc',
         'browser/extensions/api/identity/identity_api.h',
         'browser/extensions/api/offscreen_tabs/offscreen_tabs_api.cc',
         'browser/extensions/api/offscreen_tabs/offscreen_tabs_api.h',
         'browser/extensions/api/offscreen_tabs/offscreen_tabs_constants.cc',
         'browser/extensions/api/offscreen_tabs/offscreen_tabs_constants.h',
         'browser/extensions/api/omnibox/omnibox_api.cc',
         'browser/extensions/api/omnibox/omnibox_api.h',
         'browser/extensions/api/permissions/permissions_api.cc',
         'browser/extensions/api/permissions/permissions_api.h',
@@ skipping 523 matching lines @@
             'browser/extensions/api/usb/usb_api.h',
             'browser/extensions/api/usb/usb_device_resource.cc',
             'browser/extensions/api/usb/usb_device_resource.h',
           ],
         }],
       ],
     },
   ],
 }