It's a good idea to store your private keys in the cloud, even though you camouflage the file as something normal like shopping for photos on the keys and hiding the photo in a large folder of holiday photos. Your recent or something
 I think if you maintain the proper security for your cloud storage account using passwords and it is difficult to compromise with whatever you are hosting there will be safe.
 If you think that if you save a private key with Google Drive and if you think Google itself may see your private key, it is wrong.