Refactor the python system_impl module.

mojo/public/python/mojo/system.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_export  # needed so the init function gets exported
+cimport c_thunks
 
 
 from cpython.buffer cimport PyBUF_CONTIG
 from cpython.buffer cimport PyBUF_CONTIG_RO
 from cpython.buffer cimport Py_buffer
 from cpython.buffer cimport PyBuffer_FillInfo
 from cpython.buffer cimport PyBuffer_Release
 from cpython.buffer cimport PyObject_GetBuffer
 from cpython.mem cimport PyMem_Malloc, PyMem_Free
 from cpython.object cimport Py_EQ, Py_NE
 from libc.stdint cimport int32_t, int64_t, uint32_t, uint64_t, uintptr_t
 
 import ctypes
 import threading
 
 import mojo.system_impl
 
 def SetSystemThunks(system_thunks_as_object):
   """Bind the basic Mojo Core functions.
 
   This should only be used by the embedder.
   """
-  cdef const c_core.MojoSystemThunks* system_thunks = (
-      <const c_core.MojoSystemThunks*><uintptr_t>system_thunks_as_object)
-  c_core.MojoSetSystemThunks(system_thunks)
-  mojo.system_impl.SetSystemThunks(system_thunks_as_object)
+  cdef const c_thunks.MojoSystemThunks* system_thunks = (
+      <const c_thunks.MojoSystemThunks*><uintptr_t>system_thunks_as_object)
+  c_thunks.MojoSetSystemThunks(system_thunks)
 
 HANDLE_INVALID = c_core.MOJO_HANDLE_INVALID
 RESULT_OK = c_core.MOJO_RESULT_OK
 RESULT_CANCELLED = c_core.MOJO_RESULT_CANCELLED
 RESULT_UNKNOWN = c_core.MOJO_RESULT_UNKNOWN
 RESULT_INVALID_ARGUMENT = c_core.MOJO_RESULT_INVALID_ARGUMENT
 RESULT_DEADLINE_EXCEEDED = c_core.MOJO_RESULT_DEADLINE_EXCEEDED
 RESULT_NOT_FOUND = c_core.MOJO_RESULT_NOT_FOUND
 RESULT_ALREADY_EXISTS = c_core.MOJO_RESULT_ALREADY_EXISTS
 RESULT_PERMISSION_DENIED = c_core.MOJO_RESULT_PERMISSION_DENIED
@@ skipping 749 matching lines @@
     """
     return self.__run_loop.PostDelayedTask(runnable, delay)
 
   @staticmethod
   def Current():
     if hasattr(_RUN_LOOPS, 'loop'):
       return ctypes.cast(_RUN_LOOPS.loop, ctypes.py_object).value
     return None
 
 
-_ASYNC_WAITER = mojo.system_impl.ASYNC_WAITER
+_ASYNC_WAITER = mojo.system_impl.AsyncWaiter()