'Construct a ``_LoggingProcessProtocol``.
:param deferred: A ``Deferred`` that will fire with
``(reason, output)``
when the process ends, where ``reason`` is a ``Failure`` with the
reason for the process ending (see ``IProcessProtocol``), and
``output`` are the bytes outputted by the process (both to stdout
and stderr).
:param action: The Eliot ``Action`` under which this process is being
run.'

def __init__(self, deferred, action):

    self._deferred = deferred
    self._action = action
    self._output_buffer = StringIO()
