Move recipe engine to third_party/recipe_engine.

scripts/slave/recipe_modules/time/api.py

 # 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.
 
-from slave import recipe_api
+from recipe_engine import recipe_api
 
 import time
 
 class TimeApi(recipe_api.RecipeApi):
   def __init__(self, **kwargs):
     super(TimeApi, self).__init__(**kwargs)
     self._fake_time = None
     self._fake_step = None
     if self._test_data.enabled:
       self._fake_time = self._test_data.get('seed', 1337000000.0)
       self._fake_step = self._test_data.get('step', 1.5)
 
   def time(self):
     """Return current timestamp as a float number of seconds since epoch."""
     if self._test_data.enabled:
       self._fake_time += self._fake_step
       return self._fake_time
     else:  # pragma: no cover
       return time.time()