Move recipe engine to third_party/recipe_engine.

scripts/slave/recipe_modules/step/api.py

 # Copyright 2013 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 slave import recipe_util
+from recipe_engine import recipe_api
+from recipe_engine import recipe_util
 
 
 # Inherit from RecipeApiPlain because the only thing which is a step is
 # run_from_dict()
 class StepApi(recipe_api.RecipeApiPlain):
   def __init__(self, **kwargs):
     super(StepApi, self).__init__(**kwargs)
     self._step_names = {}
 
   EXCEPTION = 'EXCEPTION'
@@ skipping 100 matching lines @@
     kwargs.setdefault('cwd', self.m.path['slave_build'])
 
     schema = self.make_config()
     schema.set_val(kwargs)
     return self.run_from_dict(self._engine.create_step(schema))
 
   # TODO(martiniss) delete, and make generator_script use **kwargs on step()
   @recipe_api.composite_step
   def run_from_dict(self, dct):
     return self._engine.run_step(dct)