Add everything from src/tools/isolate r159537.

tests/isolate/touch_only.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.
+
+import os
+import sys
+
+
+def main():
+  print 'touch_only: verify the file is empty.'
+  assert len(sys.argv) == 2
+  mode = sys.argv[1]
+  assert mode in ('run', 'trace')
+
+  size = os.stat(os.path.join('files1', 'test_file1.txt')).st_size
+  if mode == 'run':
+    # The file must be empty.
+    if size:
+      print 'Unexpected content'
+      return 1
+  else:
+    # The file must be non-empty.
+    if not size:
+      print 'Unexpected emptiness'
+      return 1
+  return 0
+
+
+if __name__ == '__main__':
+  sys.exit(main())