Remove duplicated user_prefs::TestingPrefServiceSyncable

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.
 
 if (is_android) {
   import("//build/config/android/rules.gni")
 }
 
 static_library("browser") {
   sources = [
@@ skipping 144 matching lines @@
     "signin_header_helper_unittest.cc",
     "signin_investigator_unittest.cc",
     "signin_status_metrics_provider_unittest.cc",
     "webdata/token_service_table_unittest.cc",
   ]
 
   deps = [
     ":test_support",
     "//components/content_settings/core/browser",
     "//components/os_crypt:test_support",
-    "//components/pref_registry:test_support",
+    "//components/pref_registry:pref_registry",
     "//components/signin/core/common",
+    "//components/sync_preferences:test_support",
     "//testing/gmock",
   ]
 
   if (is_chromeos) {
     sources -= [
       "account_investigator_unittest.cc",
       "signin_status_metrics_provider_unittest.cc",
     ]
   }
 }
 
 if (is_android) {
   java_cpp_enum("investigated_scenario_java") {
     sources = [
       "signin_investigator.h",
     ]
   }
 }