nrwt: moving child process logging code into manager_worker_broker

nrwt: moving child process logging code into manager_worker_broker
https://bugs.webkit.org/show_bug.cgi?id=90408

Reviewed by Ojan Vafai.

Users of manager_worker_broker should not have to be aware of
whether they're in the same process or different processes and
configure logging themselves; mwb should hide this complexity.
We can't quite do this completely/correctly yet, since the
manager expects to get a list of messages to log, but this
change fixes the worker side of it, at least.

This is just moving code around, there is no new functionality
and this should be covered by existing tests.

* Scripts/webkitpy/layout_tests/controllers/manager_worker_broker.py:
(AbstractWorker.__init__):
(_WorkerConnection.__init__):
(_WorkerConnection.post_message):
(_WorkerConnection):
(_WorkerConnection.set_up_logging):
(_WorkerConnection.clean_up_logging):
(_InlineWorkerConnection.run):
(_MultiProcessWorkerConnection.run):
(_WorkerLogHandler):
(_WorkerLogHandler.__init__):
(_WorkerLogHandler.emit):
* Scripts/webkitpy/layout_tests/controllers/manager_worker_broker_unittest.py:
(_TestWorker.run):
(_TestsMixin.handle_done):
* Scripts/webkitpy/layout_tests/controllers/worker.py:
(Worker.__init__):
(Worker.run):
(Worker._run_test):
(Worker.cleanup):
(Worker.run_single_test):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@121807 268f45cc-cd09-0410-ab3c-d52691b4dbfc