Do not sync ARC opt-in preference

chrome/browser/chromeos/arc/arc_auth_service.h

Index: chrome/browser/chromeos/arc/arc_auth_service.h
diff --git a/chrome/browser/chromeos/arc/arc_auth_service.h b/chrome/browser/chromeos/arc/arc_auth_service.h
index 3466f886ad1a252bc28ddfc88d673d6b26ed6c4e..e0c4ea5a0fac2a5b0be711c5a784deaead2fb193 100644
--- a/chrome/browser/chromeos/arc/arc_auth_service.h
+++ b/chrome/browser/chromeos/arc/arc_auth_service.h
@@ -19,8 +19,6 @@
 #include "components/arc/common/auth.mojom.h"
 #include "components/arc/instance_holder.h"
 #include "components/prefs/pref_change_registrar.h"
-#include "components/syncable_prefs/pref_service_syncable_observer.h"
-#include "components/syncable_prefs/synced_pref_observer.h"
 #include "mojo/public/cpp/bindings/binding.h"
 
 class ArcAppLauncher;
@@ -47,9 +45,7 @@ class ArcAuthService : public ArcService,
                        public ArcBridgeService::Observer,
                        public InstanceHolder<mojom::AuthInstance>::Observer,
                        public ArcAndroidManagementCheckerDelegate,
-                       public ArcAuthContextDelegate,
-                       public syncable_prefs::PrefServiceSyncableObserver,
-                       public syncable_prefs::SyncedPrefObserver {
+                       public ArcAuthContextDelegate {
  public:
   enum class State {
     NOT_INITIALIZED,  // Service is not initialized.
@@ -164,12 +160,6 @@ class ArcAuthService : public ArcService,
   void EnableArc();
   void DisableArc();
 
-  // syncable_prefs::PrefServiceSyncableObserver
-  void OnIsSyncingChanged() override;
-
-  // syncable_prefs::SyncedPrefObserver
-  void OnSyncedPrefChanged(const std::string& path, bool from_sync) override;
-
   // ArcAuthContextDelegate:
   void OnContextReady() override;
   void OnPrepareContextFailed() override;