[SyncFS] Implement non-conflict local folder addition.

chrome/browser/sync_file_system/drive_backend/metadata_database.h

Index: chrome/browser/sync_file_system/drive_backend/metadata_database.h
diff --git a/chrome/browser/sync_file_system/drive_backend/metadata_database.h b/chrome/browser/sync_file_system/drive_backend/metadata_database.h
index ce1459b980fe3bad6b4f3d304f435484a09f3a27..bef7b02599ba288e60d2bb673fdbb8e155b7c2e9 100644
--- a/chrome/browser/sync_file_system/drive_backend/metadata_database.h
+++ b/chrome/browser/sync_file_system/drive_backend/metadata_database.h
@@ -268,6 +268,10 @@ class MetadataDatabase {
   // Sets |app_ids| to a list of all registered app ids.
   void GetRegisteredAppIDs(std::vector<std::string>* app_ids);
 
+  // Marks |tracker_id| dirty.
+  void MarkTrackerDirty(int64 tracker_id,
+                        const SyncStatusCallback& callback);
+
  private:
   friend class ListChangesTaskTest;
   friend class MetadataDatabaseTest;
@@ -321,6 +325,8 @@ class MetadataDatabase {
   void MaybeAddTrackersForNewFile(const FileMetadata& file,
                                   leveldb::WriteBatch* batch);
 
+  void MarkSingleTrackerDirty(FileTracker* tracker,
+                              leveldb::WriteBatch* batch);
   void MarkTrackerSetDirty(TrackerSet* trackers,
                            leveldb::WriteBatch* batch);
   void MarkTrackersDirtyByFileID(const std::string& file_id,