Convert //ios from scoped_ptr to std::unique_ptr.

ios/chrome/browser/signin/fake_signin_manager_builder.cc

 // 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/fake_signin_manager_builder.h"
 
 #include <utility>
 
 #include "components/signin/core/browser/fake_signin_manager.h"
 #include "ios/chrome/browser/browser_state/chrome_browser_state.h"
 #include "ios/chrome/browser/signin/account_tracker_service_factory.h"
 #include "ios/chrome/browser/signin/gaia_cookie_manager_service_factory.h"
 #include "ios/chrome/browser/signin/oauth2_token_service_factory.h"
 #include "ios/chrome/browser/signin/signin_client_factory.h"
 #include "ios/chrome/browser/signin/signin_manager_factory.h"
 
 namespace ios {
 
-scoped_ptr<KeyedService> BuildFakeSigninManager(
+std::unique_ptr<KeyedService> BuildFakeSigninManager(
     web::BrowserState* browser_state) {
   ios::ChromeBrowserState* chrome_browser_state =
       ios::ChromeBrowserState::FromBrowserState(browser_state);
-  scoped_ptr<SigninManager> manager(new FakeSigninManager(
+  std::unique_ptr<SigninManager> manager(new FakeSigninManager(
       SigninClientFactory::GetForBrowserState(chrome_browser_state),
       OAuth2TokenServiceFactory::GetForBrowserState(chrome_browser_state),
       ios::AccountTrackerServiceFactory::GetForBrowserState(
           chrome_browser_state),
       ios::GaiaCookieManagerServiceFactory::GetForBrowserState(
           chrome_browser_state)));
   manager->Initialize(nullptr);
   ios::SigninManagerFactory::GetInstance()
       ->NotifyObserversOfSigninManagerCreationForTesting(manager.get());
   return std::move(manager);
 }
 
 }  // namespace ios