[mb] Copy MB from Chromium repo

tools/mb/PRESUBMIT.py

+# Copyright 2016 the V8 project authors. All rights reserved.
+# Copyright 2015 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.
+
+
+def _CommonChecks(input_api, output_api):
+  results = []
+
+  # Run Pylint over the files in the directory.
+  pylint_checks = input_api.canned_checks.GetPylint(input_api, output_api)
+  results.extend(input_api.RunTests(pylint_checks))
+
+  # Run the MB unittests.
+  results.extend(input_api.canned_checks.RunUnitTestsInDirectory(
+      input_api, output_api, '.', [ r'^.+_unittest\.py$']))
+
+  # Validate the format of the mb_config.pyl file.
+  cmd = [input_api.python_executable, 'mb.py', 'validate']
+  kwargs = {'cwd': input_api.PresubmitLocalPath()}
+  results.extend(input_api.RunTests([
+      input_api.Command(name='mb_validate',
+                        cmd=cmd, kwargs=kwargs,
+                        message=output_api.PresubmitError)]))
+
+  results.extend(
+      input_api.canned_checks.CheckLongLines(
+          input_api,
+          output_api,
+          maxlen=80,
+          source_file_filter=lambda x: 'mb_config.pyl' in x.LocalPath()))
+
+  return results
+
+
+def CheckChangeOnUpload(input_api, output_api):
+  return _CommonChecks(input_api, output_api)
+
+
+def CheckChangeOnCommit(input_api, output_api):
+  return _CommonChecks(input_api, output_api)