Do not sync ARC opt-in preference

chrome/browser/chromeos/arc/arc_auth_service.cc

Index: chrome/browser/chromeos/arc/arc_auth_service.cc
diff --git a/chrome/browser/chromeos/arc/arc_auth_service.cc b/chrome/browser/chromeos/arc/arc_auth_service.cc
index 105058e76429c0910ea60c7fddb1e9116abed216..aa330059fcbee8ee03fa40d76a47d36b070dc557 100644
--- a/chrome/browser/chromeos/arc/arc_auth_service.cc
+++ b/chrome/browser/chromeos/arc/arc_auth_service.cc
@@ -153,9 +153,9 @@ ArcAuthService* ArcAuthService::Get() {
 // static
 void ArcAuthService::RegisterProfilePrefs(
     user_prefs::PrefRegistrySyncable* registry) {
-  registry->RegisterBooleanPref(
-      prefs::kArcEnabled, false,
-      user_prefs::PrefRegistrySyncable::SYNCABLE_PREF);
+  // TODO(dspaid): Implement a mechanism to allow this to sync on first boot
+  // only.
+  registry->RegisterBooleanPref(prefs::kArcEnabled, false);
   registry->RegisterBooleanPref(prefs::kArcSignedIn, false);
   registry->RegisterBooleanPref(prefs::kArcBackupRestoreEnabled, true);
   registry->RegisterBooleanPref(prefs::kArcLocationServiceEnabled, true);
@@ -519,6 +519,9 @@ void ArcAuthService::OnOptInPreferenceChanged() {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   DCHECK(profile_);
 
+  // TODO(dspaid): Move code from OnSyncedPrefChanged into this method.
+  OnSyncedPrefChanged(prefs::kArcEnabled, IsArcManaged());
+
   const bool arc_enabled = IsArcEnabled();
   FOR_EACH_OBSERVER(Observer, observer_list_, OnOptInEnabled(arc_enabled));