Add BackupRollbackController for starting backup/rollback

components/sync_driver/sync_prefs.h

Index: components/sync_driver/sync_prefs.h
diff --git a/components/sync_driver/sync_prefs.h b/components/sync_driver/sync_prefs.h
index 063c3d361960d63fede52ce069b11ead74a0d1ef..da94c5b6f36b7582f0d6cf9adfaed885c372562a 100644
--- a/components/sync_driver/sync_prefs.h
+++ b/components/sync_driver/sync_prefs.h
@@ -54,6 +54,9 @@ class SyncPrefs : NON_EXPORTED_BASE(public base::NonThreadSafe),
   // Does not take ownership of |pref_service|.
   explicit SyncPrefs(PrefService* pref_service);
 
+  // For testing.
+  SyncPrefs();
+
   virtual ~SyncPrefs();
 
   static void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry);
@@ -124,6 +127,10 @@ class SyncPrefs : NON_EXPORTED_BASE(public base::NonThreadSafe),
   // Merges the given set of types with the set of acknowledged types.
   void AcknowledgeSyncedTypes(syncer::ModelTypeSet types);
 
+  // Get/Set number of rollback attempts allowed.
+  virtual int GetRemainingRollbackTries() const;
+  virtual void SetRemainingRollbackTries(int times);
+
   // For testing.
 
   void SetManagedForTest(bool is_managed);