Move recipe engine to third_party/recipe_engine.

scripts/slave/recipe_modules/gclient/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 recipe_engine import recipe_api
 
 
 class RevisionFallbackChain(object):
   """Specify that a given project's sync revision follows the fallback chain."""
   def __init__(self, default=None):
     self._default = default
 
   def resolve(self, properties):
     """Resolve the revision via the revision fallback chain.
 
@@ skipping 288 matching lines @@
           for (path, dir, files) in os.walk(build_path):
             for cur_file in files:
               if cur_file.endswith('index.lock'):
                 path_to_file = os.path.join(path, cur_file)
                 print 'deleting %s' % path_to_file
                 os.remove(path_to_file)
       """,
       args=[self.m.path['slave_build']],
       infra_step=True,
     )