Make OAuth2TokenService and subclasses take delegate by unique_ptr

ios/chrome/browser/signin/oauth2_token_service_factory.mm

 // Copyright 2015 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.
 
 #include "ios/chrome/browser/signin/oauth2_token_service_factory.h"
 
 #include "base/memory/ptr_util.h"
 #include "base/memory/singleton.h"
 #include "components/keyed_service/ios/browser_state_dependency_manager.h"
 #include "components/pref_registry/pref_registry_syncable.h"
@@ skipping 33 matching lines @@
   registry->RegisterBooleanPref(prefs::kTokenServiceExcludeAllSecondaryAccounts,
                                 false);
   registry->RegisterListPref(prefs::kTokenServiceExcludedSecondaryAccounts);
 }
 
 std::unique_ptr<KeyedService>
 OAuth2TokenServiceFactory::BuildServiceInstanceFor(
     web::BrowserState* context) const {
   ios::ChromeBrowserState* chrome_browser_state =
       ios::ChromeBrowserState::FromBrowserState(context);
-  ProfileOAuth2TokenServiceIOSDelegate* delegate =
-      new ProfileOAuth2TokenServiceIOSDelegate(
-          SigninClientFactory::GetForBrowserState(chrome_browser_state),
-          base::MakeUnique<ProfileOAuth2TokenServiceIOSProviderImpl>(),
-          ios::AccountTrackerServiceFactory::GetForBrowserState(
-              chrome_browser_state),
-          ios::SigninErrorControllerFactory::GetForBrowserState(
-              chrome_browser_state));
-  return base::WrapUnique(new ProfileOAuth2TokenService(delegate));
+  auto delegate = base::MakeUnique<ProfileOAuth2TokenServiceIOSDelegate>(
+      SigninClientFactory::GetForBrowserState(chrome_browser_state),
+      base::MakeUnique<ProfileOAuth2TokenServiceIOSProviderImpl>(),
+      ios::AccountTrackerServiceFactory::GetForBrowserState(
+          chrome_browser_state),
+      ios::SigninErrorControllerFactory::GetForBrowserState(
+          chrome_browser_state));
+  return base::MakeUnique<ProfileOAuth2TokenService>(std::move(delegate));
 }