sync: Introduce control data types

sync/engine/conflict_util.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.
+//
+// Utility functions that act on syncable::MutableEntry to resolve conflicts.
+
+#ifndef SYNC_ENGINE_CONFLICT_UTIL_H_
+#define SYNC_ENGINE_CONFLICT_UTIL_H_
+
+namespace syncable {
+class MutableEntry;
+}
+
+namespace syncer {
+
+// Marks the item as no longer requiring sync, allowing the server's version
+// to 'win' during the next update application step.
+void IgnoreLocalChanges(syncable::MutableEntry* entry);
+
+// Marks the item as no longer requiring update from server data.  This will
+// cause the item to be committed to the server, overwriting the server's
+// version.
+void OverwriteServerChanges(syncable::MutableEntry* entry);
+
+// The local and server versions are identical, so unset the bits that put them
+// into a conflicting state.
+void IgnoreConflict(syncable::MutableEntry *trans);
+
+}  // namespace syncer
+
+#endif  // SYNC_ENGINE_CONFLICT_UTIL_H_