Add a snapshot of flutter/engine/src/build to our sdk

build/rmdir_and_stamp.py

+#!/usr/bin/env python
+# Copyright (c) 2012 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.
+
+"""Wipes out a directory recursively and then touches a stamp file.
+
+This odd pairing of operations is used to support build scripts which
+slurp up entire directories (e.g. build/android/javac.py when handling
+generated sources) as inputs.
+
+The general pattern of use is:
+
+  - Add a target which generates |gen_sources| into |out_path| from |inputs|.
+  - Include |stamp_file| as an input for that target or any of its rules which
+    generate files in |out_path|.
+  - Add an action which depends on |inputs| and which outputs |stamp_file|;
+    the action should run this script and pass |out_path| and |stamp_file| as
+    its arguments.
+
+The net result is that you will force |out_path| to be wiped and all
+|gen_sources| to be regenerated any time any file in |inputs| changes.
+
+See //third_party/mojo/mojom_bindings_generator.gypi for an example use case.
+
+"""
+
+import errno
+import os
+import shutil
+import sys
+
+
+def Main(dst_dir, stamp_file):
+  try:
+    shutil.rmtree(os.path.normpath(dst_dir))
+  except OSError as e:
+    # Ignore only "not found" errors.
+    if e.errno != errno.ENOENT:
+      raise e
+  with open(stamp_file, 'a'):
+    os.utime(stamp_file, None)
+
+if __name__ == '__main__':
+  sys.exit(Main(sys.argv[1], sys.argv[2]))