Is it possible to save Android application data in Google Cloud and sync with application while using app? E.g., I want Google Cloud Storage to act like a server for my applicat
Every google service if it access any particular user's account information or service then it has to go through oauth authentication flow. I guess you require it to access google app engine services also. https://developers.google.com/accounts/docs/OAuth2
This might not be the full answer for your question. but it can set the ball rolling.