Allow to keep old python style for existing files.

https://webrtc-review.googlesource.com/c/src/+/321081 made PEP-8 mandatory for WebRTC python file.

This CL allows to keep the old formatting style for existing python files because switching all methods and functions name from PascalCase to snake_case is non trivial.

Change-Id: Id094bbf72ee1c3c32027a49bc9763bc65dfb9ad2
Bug: None
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/323860
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Jeremy Leconte <jleconte@google.com>
Reviewed-by: Christoffer Jansson <jansson@google.com>
Cr-Commit-Position: refs/heads/main@{#40951}

OWNERS_INFRA

@@ -10,6 +10,7 @@ per-file .vpython3=mbonadei@webrtc.org,jansson@webrtc.org,jleconte@webrtc.org
 per-file AUTHORS=*
 per-file DEPS=*
 per-file pylintrc=mbonadei@webrtc.org,jansson@webrtc.org,jleconte@webrtc.org
+per-file pylintrc_old_style=mbonadei@webrtc.org,jansson@webrtc.org,jleconte@webrtc.org
 per-file WATCHLISTS=*
 per-file native-api.md=mbonadei@webrtc.org
 per-file ....lua=titovartem@webrtc.org

pylintrc_old_style

@@ -0,0 +1,216 @@
+# Copyright (c) 2015 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 file is mostly based on the contents of
+# https://cs.chromium.org/chromium/tools/depot_tools/pylintrc
+# and (since the above doesn't properly support naming style checks)
+# https://cs.chromium.org/chromium/src/third_party/chromite/pylintrc
+
+[MESSAGES CONTROL]
+
+# Disable the message, report, category or checker with the given id(s).
+# TODO(kjellander): Reduce this list to as small as possible.
+disable=
+  E0611,
+  I0010,
+  I0011,
+  W0232,
+  C0413,
+  bad-continuation,
+  broad-except,
+  duplicate-code,
+  eval-used,
+  exec-used,
+  fixme,
+  import-error,
+  import-outside-toplevel,
+  missing-docstring,
+  no-init,
+  no-member,
+  too-few-public-methods,
+  too-many-ancestors,
+  too-many-arguments,
+  too-many-branches,
+  too-many-function-args,
+  too-many-instance-attributes,
+  too-many-lines,
+  too-many-locals,
+  too-many-public-methods,
+  too-many-return-statements,
+  too-many-statements,
+
+
+[REPORTS]
+
+# Don't write out full reports, just messages.
+reports=no
+
+
+[VARIABLES]
+
+# Tells whether we should check for unused import in __init__ files.
+init-import=no
+
+# A regular expression matching the beginning of the name of dummy variables
+# (i.e. not used).
+dummy-variables-rgx=_|dummy
+
+
+[TYPECHECK]
+
+# Tells whether missing members accessed in mixin class should be ignored. A
+# mixin class is detected if its name ends with "mixin" (case insensitive).
+ignore-mixin-members=yes
+
+# List of classes names for which member attributes should not be checked
+# (useful for classes with attributes dynamically set).
+ignored-classes=hashlib,numpy
+
+
+[MISCELLANEOUS]
+
+# List of note tags to take in consideration, separated by a comma.
+notes=FIXME,XXX,TODO
+
+
+[SIMILARITIES]
+
+# Minimum lines number of a similarity.
+min-similarity-lines=4
+
+# Ignore comments when computing similarities.
+ignore-comments=yes
+
+# Ignore docstrings when computing similarities.
+ignore-docstrings=yes
+
+
+[FORMAT]
+
+# Maximum number of characters on a single line.
+max-line-length=80
+
+# Maximum number of lines in a module
+max-module-lines=1000
+
+# Use four spaces for indents.
+# indent-string='    '
+
+
+[BASIC]
+
+# List of builtins function names that should not be used, separated by a comma
+bad-functions=map,filter,apply,input
+
+# Regular expression which should only match correct module names
+module-rgx=(([a-z_][a-z0-9_]*)|([A-Z][a-zA-Z0-9]+))$
+
+# Regular expression which should only match correct module level names
+# (CAPS_WITH_UNDER)
+const-rgx=(([A-Z_][A-Z0-9_]*)|(__.*__))$
+
+# Regular expression which should only match correct class names
+# (CapWords)
+class-rgx=[A-Z_][a-zA-Z0-9]+$
+
+# Regular expression which should only match correct function names
+# The Chromium standard is different than PEP-8, so we need to redefine this to
+# only allow:
+# - CapWords
+# - main: Standard for main function.
+function-rgx=([A-Z_][a-zA-Z0-9]{2,60}|main)$
+
+# Regular expression which should only match correct method names
+# The Chromium standard is different than PEP-8, so we need to redefine this to
+# only allow:
+# - CapWords, starting with a capital letter.  No underscores in function
+#   names.  Can also have a "_" prefix (private method) or a "test" prefix
+#   (unit test).
+# - Methods that look like __xyz__, which are used to do things like
+#   __init__, __del__, etc.
+# - setUp, tearDown: For unit tests.
+method-rgx=((_|test)?[A-Z][a-zA-Z0-9]{2,60}|__[a-z]+__|setUp|tearDown)$
+
+# Regular expression which should only match correct instance attribute names
+attr-rgx=[a-z_][a-z0-9_]{2,30}$
+
+# Regular expression which should only match correct argument names
+argument-rgx=[a-z_][a-z0-9_]{2,30}$
+
+# Regular expression which should only match correct variable names
+variable-rgx=[a-z_][a-z0-9_]{0,30}$
+
+# Regular expression which should only match correct list comprehension /
+# generator expression variable names
+inlinevar-rgx=[A-Za-z_][A-Za-z0-9_]*$
+
+# Good variable names which should always be accepted, separated by a comma
+good-names=i,j,k,ex,Run,_
+
+# Bad variable names which should always be refused, separated by a comma
+bad-names=foo,bar,baz,toto,tutu,tata
+
+# Regular expression which should only match functions or classes name which do
+# not require a docstring
+no-docstring-rgx=__.*__
+
+
+[DESIGN]
+
+# Maximum number of arguments for function / method
+max-args=5
+
+# Argument names that match this expression will be ignored. Default to name
+# with leading underscore
+ignored-argument-names=_.*
+
+# Maximum number of locals for function / method body
+max-locals=15
+
+# Maximum number of return / yield for function / method body
+max-returns=6
+
+# Maximum number of branch for function / method body
+max-branchs=12
+
+# Maximum number of statements in function / method body
+max-statements=50
+
+# Maximum number of parents for a class (see R0901).
+max-parents=7
+
+# Maximum number of attributes for a class (see R0902).
+max-attributes=7
+
+# Minimum number of public methods for a class (see R0903).
+min-public-methods=2
+
+# Maximum number of public methods for a class (see R0904).
+max-public-methods=20
+
+
+[CLASSES]
+
+# List of method names used to declare (i.e. assign) instance attributes.
+defining-attr-methods=__init__,__new__,setUp
+
+# List of valid names for the first argument in a class method.
+valid-classmethod-first-arg=cls
+
+
+[IMPORTS]
+
+# Deprecated modules which should not be used, separated by a comma
+deprecated-modules=regsub,TERMIOS,Bastion,rexec
+
+
+[EXCEPTIONS]
+
+# Exceptions that will emit a warning when being caught. Defaults to
+# "Exception"
+overgeneral-exceptions=Exception