depot_tools: add presubmit recipe module

recipe_modules/presubmit/api.py

Index: recipe_modules/presubmit/api.py
diff --git a/recipe_modules/presubmit/api.py b/recipe_modules/presubmit/api.py
new file mode 100644
index 0000000000000000000000000000000000000000..3fbf3169091346aeb45df1064ff2a6327c099fca
--- /dev/null
+++ b/recipe_modules/presubmit/api.py
@@ -0,0 +1,13 @@
+# Copyright 2016 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 recipe_engine import recipe_api
+
+class PresubmitApi(recipe_api.RecipeApi):
+  def __call__(self, *args, **kwargs):
+    """Return a presubmit step."""
+    name = kwargs.pop('name', 'presubmit')
+    return self.m.python(
+        name, self.package_resource('presubmit_support.py'), list(args),
+        **kwargs)