Ensure that the Service proxy has established a session with the Secret Service.
This session is used to transfer secrets.
It is not normally necessary to call this method, as the session is established as necessary. You can also pass the
OPEN_SESSION to [funcService.get] in order to ensure
that a session has been established by the time you get the Service proxy.
This method will return immediately and complete asynchronously.
| this |
the secret service |
| cancellable |
optional cancellation object |
| callback |
called when the operation completes |
| user_data |
data to be passed to the callback |