Update GN build files for new prefs location.

components/signin/ios/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.
 
 source_set("browser") {
   sources = [
     "account_consistency_service.h",
     "account_consistency_service.mm",
     "manage_accounts_delegate.h",
     "merge_session_observer_bridge.h",
     "merge_session_observer_bridge.mm",
     "oauth2_token_service_observer_bridge.h",
     "oauth2_token_service_observer_bridge.mm",
     "profile_oauth2_token_service_ios_delegate.h",
     "profile_oauth2_token_service_ios_delegate.mm",
     "profile_oauth2_token_service_ios_provider.h",
   ]
 
   deps = [
     "//base",
-    "//base:prefs",
     "//components/content_settings/core/browser",
     "//components/google/core/browser",
     "//components/keyed_service/core",
     "//components/pref_registry",
+    "//components/prefs",
     "//components/signin/core/browser",
     "//components/signin/core/common",
     "//google_apis",
     "//ios/web",
     "//net",
   ]
 }
 
 source_set("test_support") {
   testonly = true
@@ skipping 13 matching lines @@
 
 source_set("unit_tests") {
   testonly = true
   sources = [
     "account_consistency_service_unittest.mm",
     "profile_oauth2_token_service_ios_delegate_unittest.mm",
   ]
 
   deps = [
     ":test_support",
-    "//base:prefs",
-    "//base:prefs_test_support",
     "//components/pref_registry:test_support",
+    "//components/prefs:test_support",
     "//components/signin/core/browser",
     "//components/signin/core/browser:test_support",
     "//components/signin/core/common",
     "//ios/web",
     "//ios/web:test_support",
     "//third_party/ocmock",
   ]
 }