Retrieve the element with the given key
Requires the allow:localstorage permission.
Set the data given the key. If the value already existed it
will be overriden. The value will be stored in a string representation.
Requires the allow:localstorage permission.
Remove the value stored in the key.
Requires the allow:localstorage permission.
Return all the keys for the data stored by the plugin.
Requires the allow:localstorage permission.
Proxy for the local storage. Only elements owned by the plugin can be stored and accessed. Warning: other plugins won't be able to access this information but the user could potentialy access the data through the browser information.