Authenticates the ClientLoginAuthorizer with the Google accounts service
using the given username and password.
this, username and password are all reffed/copied when this function is
called, so can safely be freed after this function returns.
For more details, see authenticate, which is the synchronous version of this function.
When the operation is finished, callback will be called. You can then call authenticate_async.end
to get the results of the operation.
| this | |
| username |
the user's username |
| password |
the user's password |
| cancellable |
optional Cancellable object, or null |
| callback |
a TaskReadyCallback to call when authentication is finished |
| user_data |
data to pass to the |