Nilay Patel does a nice job explaining Google Drive’s terms of service:
That’s a lot of rights to give Google, on the face of it — in fact, it’s basically every right you can give to Google as a copyright holder. But think about how limited Google’s services would be if it didn’t have permission to use, host, store, modify, communicate, publish, or distribute your content — it couldn’t move files around on its servers, cache your data, or make image thumbnails, since those would be unauthorized copies. It couldn’t run Google Translate or Google Image Search. It would be illegal to play YouTube clips in public. In short, Google is giving itself all the permissions it could possibly need to run all of Google services, with the specific limitations that it doesn’t own anything you upload and it can’t use your data beyond running its services.
So, no, they’re not going to take your work and use it for themselves. We can all shut off the alarm bells.