This is what I have found on the Google developer page:
Quote: "
This class provides access to a centralized registry of the user's online accounts. The user enters credentials (username and password) once per account, granting applications access to online resources with "one-click" approval.
Different online services have different ways of handling accounts and authentication, so the account manager uses pluggable authenticator modules for different account types. Authenticators (which may be written by third parties) handle the actual details of validating account credentials and storing account information. For example, Google, Facebook, and Microsoft Exchange each have their own authenticator.
Many servers support some notion of an authentication token, which can be used to authenticate a request to the server without sending the user's actual password. (Auth tokens are normally created with a separate request which does include the user's credentials.) AccountManager can generate auth tokens for applications, so the application doesn't need to handle passwords directly. Auth tokens are normally reusable and cached by AccountManager, but must be refreshed periodically. It's the responsibility of applications to invalidate auth tokens when they stop working so the AccountManager knows it needs to regenerate them.
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Hope it will help you.
