Add everything from src/tools/isolate r159537.

README.py

Index: README.py
diff --git a/README.py b/README.py
new file mode 100755
index 0000000000000000000000000000000000000000..e5652602fdd15f911641d47c2d312afd89a64c6a
--- /dev/null
+++ b/README.py
@@ -0,0 +1,46 @@
+#!/usr/bin/env python
+# coding=utf-8
+# 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.
+
+###
+# Run me to generate the documentation!
+###
+
+"""Test tracing and isolation infrastructure.
+
+Scripts are compartmentalized by their name:
+- trace_*.py: Tracing infrastructure scripts.
+- isolate_*.py: Executable isolation scripts. (TODO)
+- *_test_cases.py: Scripts specifically managing GTest executables.
+
+A few scripts have strict dependency rules:
+- run_swarm_step.py, run_test_cases.py, shard_test_cases.py and trace_inputs.py
+  depends on no other script so they can be run outside the checkout.
+- The pure tracing scripts (trace_inputs.py and trace_test_cases.py) do not know
+  about isolate infrastructure.
+- Scripts without _test_cases suffix do not know about GTest.
+- Scripts without isolate_ prefix do not know about the isolation
+  infrastructure. (TODO)
+
+See http://dev.chromium.org/developers/testing/isolated-testing for more info.
+"""
+
+import os
+import sys
+
+
+def main():
+  for i in sorted(os.listdir(os.path.dirname(os.path.abspath(__file__)))):
+    if not i.endswith('.py') or i == 'PRESUBMIT.py':
+      continue
+    module = __import__(i[:-3])
+    if hasattr(module, '__doc__'):
+      print module.__name__
+      print ''.join('  %s\n' % i for i in module.__doc__.splitlines())
+  return 0
+
+
+if __name__ == '__main__':
+  sys.exit(main())