Move recipe engine to third_party/recipe_engine.

scripts/slave/recipe_modules/repo/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.
 
 """Common steps for recipes that use repo for source control."""
 
 import re
 
-from slave import recipe_api
+from recipe_engine import recipe_api
 
 class RepoApi(recipe_api.RecipeApi):
   """Provides methods to encapsulate repo operations."""
 
   _REPO_LIST_RE = re.compile(r'^(.+) : (.+)$')
 
   # WARNING: The version of repo checked into depot_tools doesn't support
   # switching between branches correctly due to
   # https://code.google.com/p/git-repo/issues/detail?id=46
 
@@ skipping 68 matching lines @@
       match = self._REPO_LIST_RE.match(line)
       if match:
         result.append(match.groups())
 
     # Display the result in the step text.
     if result:
       step_result.presentation.step_text = '</br></br>'
       step_result.presentation.step_text += '</br>'.join(
           '%s : %s' % (path, name) for path, name in result)
     return result