sync: Attempt to recover from directory corruption

sync/syncable/directory_backing_store.h

 // Copyright (c) 2012 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.
 
 #ifndef SYNC_SYNCABLE_DIRECTORY_BACKING_STORE_H_
 #define SYNC_SYNCABLE_DIRECTORY_BACKING_STORE_H_
 
 #include <string>
 
 #include "base/memory/scoped_ptr.h"
@@ skipping 108 matching lines @@
   static ModelType ModelIdToModelTypeEnum(const void* data, int length);
   static std::string ModelTypeEnumToModelId(ModelType model_type);
 
   static std::string GenerateCacheGUID();
 
   // Runs an integrity check on the current database.  If the
   // integrity check fails, false is returned and error is populated
   // with an error message.
   bool CheckIntegrity(sqlite3* handle, std::string* error) const;
 
+  // Checks that the references between sync nodes is consistent.
+  static bool VerifyReferenceIntegrity(const MetahandlesIndex& entries);
+
   // Migration utilities.
   bool RefreshColumns();
   bool SetVersion(int version);
   int GetVersion();
 
   bool MigrateToSpecifics(const char* old_columns,
                           const char* specifics_column,
                           void(*handler_function) (
                               sql::Statement* old_value_query,
                               int old_value_column,
@@ skipping 20 matching lines @@
   // discarded.
   bool needs_column_refresh_;
 
   DISALLOW_COPY_AND_ASSIGN(DirectoryBackingStore);
 };
 
 }  // namespace syncable
 }  // namespace syncer
 
 #endif  // SYNC_SYNCABLE_DIRECTORY_BACKING_STORE_H_