This is a free lock/unlock app for Google Drive™ that provides convenient way to restrict multiple files with fast, easy and minimal operations.
You can add and remove content restrictions. Any file type in Drive can be locked/unlocked preventing changes to the item’s content, title, and comments.
Provides connect with Google Drive™.

Content restrictions can also be removed (but not added) via the Drive Web UI Unlock action menu. Adding or removing a content restriction requires at least writer(edit) permission.
You can make multiple files to readonly restrictions directly.