Make the ARC opt-in preference not synced.

chrome/browser/chromeos/arc/arc_auth_service.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 "chrome/browser/chromeos/arc/arc_auth_service.h"
 
 #include <utility>
 
 #include "ash/shelf/shelf_delegate.h"
 #include "ash/shell.h"
@@ skipping 102 matching lines @@
 
 // static
 ArcAuthService* ArcAuthService::Get() {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   return g_arc_auth_service;
 }
 
 // static
 void ArcAuthService::RegisterProfilePrefs(
     user_prefs::PrefRegistrySyncable* registry) {
-  registry->RegisterBooleanPref(
-      prefs::kArcEnabled, false,
-      user_prefs::PrefRegistrySyncable::SYNCABLE_PREF);
+  // TODO(dspaid): Add a syncable default preference so that new
+  // devices get the last opt-in preference.
+  registry->RegisterBooleanPref(prefs::kArcEnabled, false);
   registry->RegisterBooleanPref(prefs::kArcSignedIn, false);
   registry->RegisterBooleanPref(prefs::kArcBackupRestoreEnabled, true);
 }
 
 // static
 void ArcAuthService::DisableUIForTesting() {
   g_disable_ui_for_testing = true;
 }
 
 // static
@@ skipping 626 matching lines @@
       return os << kStateFetchingCode;
     case ArcAuthService::State::ACTIVE:
       return os << kStateActive;
     default:
       NOTREACHED();
       return os;
   }
 }
 
 }  // namespace arc