[SyncFileSystem][Clean up] Delete DriveMetadataDB::DeleteEntry.

chrome/browser/sync_file_system/drive_metadata_store.h

Index: chrome/browser/sync_file_system/drive_metadata_store.h
diff --git a/chrome/browser/sync_file_system/drive_metadata_store.h b/chrome/browser/sync_file_system/drive_metadata_store.h
index 9c08c8a31386b5fef6f681cf34bd0b112ae95951..987e5a33469d372fe965d39a7915e93b99d5c220 100644
--- a/chrome/browser/sync_file_system/drive_metadata_store.h
+++ b/chrome/browser/sync_file_system/drive_metadata_store.h
@@ -26,6 +26,7 @@ class SequencedTaskRunner;
 
 namespace leveldb {
 class DB;
+class WriteBatch;
 }
 
 class GURL;
@@ -149,6 +150,9 @@ class DriveMetadataStore
  private:
   friend class DriveMetadataStoreTest;
 
+  void WriteToDB(scoped_ptr<leveldb::WriteBatch> batch,
+                 const SyncStatusCallback& callback);
+
   void UpdateDBStatus(SyncStatusCode status);
   void UpdateDBStatusAndInvokeCallback(const SyncStatusCallback& callback,
                                        SyncStatusCode status);