Refactor AO2TS to make it easier to componentize.

components/signin/core/browser/BUILD.gn

 # Copyright 2014 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.
 
 static_library("browser") {
   sources = [
     "about_signin_internals.cc",
     "about_signin_internals.h",
     "account_reconcilor.cc",
     "account_reconcilor.h",
     "account_service_flag_fetcher.cc",
     "account_service_flag_fetcher.h",
     "account_tracker_service.cc",
     "account_tracker_service.h",
     "gaia_cookie_manager_service.cc",
     "gaia_cookie_manager_service.h",
-    "mutable_profile_oauth2_token_service.cc",
-    "mutable_profile_oauth2_token_service.h",
     "profile_oauth2_token_service.cc",
     "profile_oauth2_token_service.h",
     "refresh_token_annotation_request.cc",
     "refresh_token_annotation_request.h",
     "signin_client.h",
     "signin_error_controller.cc",
     "signin_error_controller.h",
     "signin_internals_util.cc",
     "signin_internals_util.h",
     "signin_manager.cc",
@@ skipping 23 matching lines @@
     "//net",
     "//sql",
     "//third_party/icu",
     "//components/content_settings/core/browser",
     "//components/content_settings/core/common",
     "//components/keyed_service/core",
     "//components/os_crypt",
     "//components/webdata/common",
   ]
 
-  if (is_android) {
-    sources -= [
-      "mutable_profile_oauth2_token_service.cc",
-      "mutable_profile_oauth2_token_service.h",
-    ]
-  }
-
   if (is_chromeos) {
     sources -= [ "signin_manager.cc" ]
   }
 }
 
 static_library("test_support") {
   testonly = true
   sources = [
     "fake_auth_status_provider.cc",
     "fake_auth_status_provider.h",
     "test_signin_client.cc",
     "test_signin_client.h",
   ]
 
   deps = [
     ":browser",
     "//testing/gtest",
   ]
 }