[Sync] Rely on directory to decide which types need to be purged

chrome/browser/sync/glue/sync_backend_host_impl.cc

 // Copyright 2013 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/sync/glue/sync_backend_host_impl.h"
 
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chrome_notification_types.h"
@@ skipping 321 matching lines @@
   // must ask the syncer to download them.  Any newly supported datatypes will
   // not have been in that routing info list, so they will be among the types
   // downloaded if they are enabled.
   //
   // The SyncBackendRegistrar's state was initially derived from the types
   // detected to have been downloaded in the database.  Afterwards it is
   // modified only by this function.  We expect it to remain in sync with the
   // backend because configuration requests are never aborted; they are retried
   // until they succeed or the backend is shut down.
 
-  syncer::ModelTypeSet previous_types = registrar_->GetLastConfiguredTypes();
-
   syncer::ModelTypeSet disabled_types =
       GetDataTypesInState(DISABLED, config_state_map);
   syncer::ModelTypeSet fatal_types =
       GetDataTypesInState(FATAL, config_state_map);
   syncer::ModelTypeSet crypto_types =
       GetDataTypesInState(CRYPTO, config_state_map);
   syncer::ModelTypeSet unready_types =
       GetDataTypesInState(UNREADY, config_state_map);
+
   disabled_types.PutAll(fatal_types);
-
-  // TODO(zea): These types won't be fully purged if they are subsequently
-  // disabled by the user. Fix that. See crbug.com/386778
   disabled_types.PutAll(crypto_types);
   disabled_types.PutAll(unready_types);
 
   syncer::ModelTypeSet active_types =
       GetDataTypesInState(CONFIGURE_ACTIVE, config_state_map);
   syncer::ModelTypeSet clean_first_types =
       GetDataTypesInState(CONFIGURE_CLEAN, config_state_map);
   syncer::ModelTypeSet types_to_download = registrar_->ConfigureDataTypes(
       syncer::Union(active_types, clean_first_types),
       disabled_types);
@@ skipping 22 matching lines @@
   // will not send a MIGRATION_DONE response in that case.  We still need to be
   // careful to not send progress markers for non-nigori types, though.  If a
   // non-nigori type in the request requires migration, a MIGRATION_DONE
   // response will be sent.
 
   syncer::ModelSafeRoutingInfo routing_info;
   registrar_->GetModelSafeRoutingInfo(&routing_info);
 
   syncer::ModelTypeSet current_types = registrar_->GetLastConfiguredTypes();
   syncer::ModelTypeSet types_to_purge =
-      syncer::Difference(previous_types, current_types);
+      syncer::Difference(syncer::ModelTypeSet::All(), current_types);
   syncer::ModelTypeSet inactive_types =
       GetDataTypesInState(CONFIGURE_INACTIVE, config_state_map);
   types_to_purge.RemoveAll(inactive_types);
   types_to_purge.RemoveAll(unready_types);
 
   // If a type has already been disabled and unapplied or journaled, it will
   // not be part of the |types_to_purge| set, and therefore does not need
   // to be acted on again.
   fatal_types.RetainAll(types_to_purge);
   syncer::ModelTypeSet unapply_types =
@@ skipping 467 matching lines @@
 
 base::MessageLoop* SyncBackendHostImpl::GetSyncLoopForTesting() {
   return registrar_->sync_thread()->message_loop();
 }
 
 }  // namespace browser_sync
 
 #undef SDVLOG
 
 #undef SLOG