Refactor the python system_impl module.

mojo/public/python/mojo/system_impl.pyx

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # distutils language = c++
 
 cimport c_core
 cimport c_environment
+cimport c_async_waiter
 
 
 from libc.stdint cimport uintptr_t
 
+
 def SetSystemThunks(system_thunks_as_object):
   """Bind the basic Mojo Core functions.
   """
   cdef const c_core.MojoSystemThunks* system_thunks = (
       <const c_core.MojoSystemThunks*><uintptr_t>system_thunks_as_object)
   c_core.MojoSetSystemThunks(system_thunks)
 
 
 cdef class RunLoop(object):
   """RunLoop to use when using asynchronous operations on handles."""
@@ skipping 23 matching lines @@
     """
     Post a task on the runloop. This must be called from the thread owning the
     runloop.
     """
     cdef c_environment.CClosure closure = c_environment.BuildClosure(runnable)
     self.c_run_loop.PostDelayedTask(closure, delay)
 
 
 # We use a wrapping class to be able to call the C++ class PythonAsyncWaiter
 # across module boundaries.
-cdef class _AsyncWaiter(object):
+cdef class AsyncWaiter(object):
   cdef c_environment.CEnvironment* _cenvironment
-  cdef c_environment.PythonAsyncWaiter* _c_async_waiter
+  cdef c_async_waiter.PythonAsyncWaiter* _c_async_waiter
 
   def __init__(self):
     self._cenvironment = new c_environment.CEnvironment()
-    self._c_async_waiter = new c_environment.PythonAsyncWaiter()
+    self._c_async_waiter = c_environment.NewAsyncWaiter()
 
   def __dealloc__(self):
     del self._c_async_waiter
     del self._cenvironment
 
   def AsyncWait(self, handle, signals, deadline, callback):
     return self._c_async_waiter.AsyncWait(handle, signals, deadline, callback)
 
   def CancelWait(self, wait_id):
     self._c_async_waiter.CancelWait(wait_id)
-
-
-ASYNC_WAITER = _AsyncWaiter()