Adds a new checkbox for backup and restore in opt-in flow.

chrome/browser/prefs/browser_prefs.cc

 // Copyright 2012 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 "chrome/browser/prefs/browser_prefs.h"
 
 #include <string>
 
 #include "base/metrics/histogram_macros.h"
 #include "base/trace_event/trace_event.h"
@@ skipping 348 matching lines @@
   StartupBrowserCreator::RegisterLocalStatePrefs(registry);
   // The native GCM is used on Android instead.
   gcm::GCMChannelStatusSyncer::RegisterPrefs(registry);
   UpgradeDetector::RegisterPrefs(registry);
 #if !defined(OS_CHROMEOS)
   RegisterDefaultBrowserPromptPrefs(registry);
 #endif  // !defined(OS_CHROMEOS)
 #endif  // !defined(OS_ANDROID)
 
 #if defined(OS_CHROMEOS)
+  arc::ArcAuthService::RegisterPrefs(registry);
   ChromeOSMetricsProvider::RegisterPrefs(registry);
   chromeos::AudioDevicesPrefHandlerImpl::RegisterPrefs(registry);
   chromeos::ChromeUserManagerImpl::RegisterPrefs(registry);
   chromeos::DataPromoNotification::RegisterPrefs(registry);
   chromeos::DeviceOAuth2TokenService::RegisterPrefs(registry);
   chromeos::device_settings_cache::RegisterPrefs(registry);
   chromeos::EnableDebuggingScreenHandler::RegisterPrefs(registry);
   chromeos::language_prefs::RegisterPrefs(registry);
   chromeos::KioskAppManager::RegisterPrefs(registry);
   chromeos::MultiProfileUserController::RegisterPrefs(registry);
@@ skipping 328 matching lines @@
     profile_prefs->SetInt64(prefs::kDefaultBrowserLastDeclined,
                             install_time.ToInternalValue());
   }
   profile_prefs->ClearPref(kCheckDefaultBrowser);
 
   // Added 5/2016.
   profile_prefs->ClearPref(kDesktopSearchRedirectionInfobarShownPref);
 }
 
 }  // namespace chrome