Refactor the python system_impl module.

mojo/public/python/mojo/c_environment.pxd

Index: mojo/public/python/mojo/c_environment.pxd
diff --git a/mojo/public/python/mojo/c_environment.pxd b/mojo/public/python/mojo/c_environment.pxd
index 3dfa79960ed5c17786b91e364f572f7099d0ab0c..c1b37d6a1f0cb52fd55b94ce5384d0c14d5c710c 100644
--- a/mojo/public/python/mojo/c_environment.pxd
+++ b/mojo/public/python/mojo/c_environment.pxd
@@ -6,11 +6,7 @@
 
 from libc.stdint cimport int64_t, intptr_t, uint32_t, uint64_t
 
-
-cdef extern from "mojo/public/c/system/core.h" nogil:
-  ctypedef uint32_t MojoHandle
-  ctypedef uint64_t MojoDeadline
-  ctypedef uint32_t MojoHandleSignals
+cimport c_async_waiter
 
 
 cdef extern from "mojo/public/cpp/bindings/callback.h" nogil:
@@ -18,20 +14,10 @@ cdef extern from "mojo/public/cpp/bindings/callback.h" nogil:
     CClosure()
 
 
-cdef extern from "mojo/public/c/environment/async_waiter.h"  nogil:
-  ctypedef intptr_t MojoAsyncWaitID
-
-
 cdef extern from "mojo/public/python/src/python_system_helper.h" \
     namespace "mojo::python" nogil:
   cdef CClosure BuildClosure(object)
-  cdef cppclass PythonAsyncWaiter "mojo::python::PythonAsyncWaiter":
-    PythonAsyncWaiter()
-    MojoAsyncWaitID AsyncWait(MojoHandle,
-                              MojoHandleSignals,
-                              MojoDeadline,
-                              object)
-    void CancelWait(MojoAsyncWaitID)
+  cdef c_async_waiter.PythonAsyncWaiter* NewAsyncWaiter()
 
 
 cdef extern from "mojo/public/cpp/utility/run_loop.h" nogil: