Fixing relative paths and adding a docstring

tools-webrtc/gn_check_autofix.py

 #!/usr/bin/env python
 
 # Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
+"""
+This tool tries to fix (some) errors reported by `gn gen --check` or
+`gn check`.
+It will run `mb gen` in a temporary directory and it is really useful to
+check for different configurations.
+
+Usage:
+    $ python tools-webrtc/gn_check_autofix.py -m some_mater -b some_bot
+    or
+    $ python tools-webrtc/gn_check_autofix.py -c some_mb_config
+"""
+
 import os
 import re
 import shutil
 import subprocess
 import sys
 import tempfile
 
 from collections import defaultdict
 
 TARGET_RE = re.compile(
@@ skipping 69 matching lines @@
   dependency_path = dependency_path[first_difference:]
   return (os.path.sep.join((['..'] * len(base_path)) + dependency_path) +
           ':' + dependency)
 
 def main():
   deleted_sources = set()
   errors_by_file = defaultdict(lambda: defaultdict(set))
 
   with TemporaryDirectory() as tmp_dir:
     mb_gen_command = ([
-        'tools/mb/mb.py', 'gen',
+        'tools-webrtc/mb/mb.py', 'gen',

[kjellander_webrtc, 2016/12/20 13:35:55]

I'm a bit curious how this works. Does the script only work when being run from
the src/ directory as current working directory? 

Not that we have to fix that, but usually I use something like SCRIPT_DIR:
https://cs.chromium.org/chromium/src/third_party/webrtc/tools/compare_videos....
then I do os.path.join(SCRIPT_DIR...
to get absolute paths.

[mbonadei, 2016/12/20 13:47:38]

Yep, it works only if it is run from `src`. I agree that this should be
documented or fixed. Let me fix it.

         tmp_dir,
-        '--config-file', 'webrtc/build/mb_config.pyl',
+        '--config-file', 'tools-webrtc/mb/mb_config.pyl',
     ] + sys.argv[1:])
 
   mb_output = Run(mb_gen_command)
   errors = mb_output[0].split('ERROR')[1:]
 
   if mb_output[1]:
     print mb_output[1]
     return 1
 
   for error in errors:
@@ skipping 20 matching lines @@
       print '\n'.join(error)
       continue
 
   for path, missing_deps in errors_by_file.items():
     FixErrors(path, missing_deps, deleted_sources)
 
   return 0
 
 if __name__ == '__main__':
   sys.exit(main())