Revert 148792 - [Sync] Remove CleanupDisabledTypes command and move purge logic into SyncManager.

sync/internal_api/sync_manager_impl.h

Index: sync/internal_api/sync_manager_impl.h
===================================================================
--- sync/internal_api/sync_manager_impl.h	(revision 148811)
+++ sync/internal_api/sync_manager_impl.h	(working copy)
@@ -180,7 +180,6 @@
   FRIEND_TEST_ALL_PREFIXES(SyncManagerTest, NudgeDelayTest);
   FRIEND_TEST_ALL_PREFIXES(SyncManagerTest, OnNotificationStateChange);
   FRIEND_TEST_ALL_PREFIXES(SyncManagerTest, OnIncomingNotification);
-  FRIEND_TEST_ALL_PREFIXES(SyncManagerTest, PurgeDisabledTypes);
 
   struct NotificationInfo {
     NotificationInfo();
@@ -228,11 +227,6 @@
   // went wrong.
   bool SignIn(const SyncCredentials& credentials);
 
-  // Purge those types from |previously_enabled_types| that are no longer
-  // enabled in |currently_enabled_types|.
-  bool PurgeDisabledTypes(ModelTypeSet previously_enabled_types,
-                          ModelTypeSet currently_enabled_types);
-
   void RequestNudgeForDataTypes(
       const tracked_objects::Location& nudge_location,
       ModelTypeSet type);