[chrome_remote_control] Add pylint to PRESUMMIT and fix lint

tools/chrome_remote_control/chrome_remote_control/system_stub.py

 # 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 as real_os
-import sys as real_sys
-import subprocess as real_subprocess
-
 """Provides stubs for os, sys and subprocess for testing
 
 This test allows one to test code that itself uses os, sys, and subprocess.
 """
+import os as real_os
+import subprocess as real_subprocess
+
 class SysModuleStub(object):
   def __init__(self):
     self.platform = ''
 
 class OSPathModuleStub(object):
   def __init__(self, os_module_stub):
     self._os_module_stub = os_module_stub
 
   def exists(self, path):
     return path in self._os_module_stub.files
 
   def join(self, *args):
     if self._os_module_stub.sys.platform.startswith('win'):
       tmp = real_os.path.join(*args)
       return tmp.replace('/', '\\')
     else:
       return real_os.path.join(*args)
 
-  def dirname(self, filename):
+  def dirname(self, filename): # pylint: disable=R0201
     return real_os.path.dirname(filename)
 
 class OSModuleStub(object):
   def __init__(self, sys):
     self.sys = sys
     self.path = OSPathModuleStub(self)
     self.files = []
     self.display = ':0'
     self.local_app_data = None
 
   def getenv(self, name):
     if name == 'DISPLAY':
       return self.display
     if name == 'LOCALAPPDATA':
       return self.local_app_data
     raise Exception('Unsupported getenv')
 
 class PopenStub(object):
   def __init__(self, communicate_result):
     self.communicate_result = communicate_result
 
   def communicate(self):
     return self.communicate_result
 
 class SubprocessModuleStub(object):
   def __init__(self):
     self.Popen_hook = None
     self.Popen_result = None
-    import subprocess as real_subprocess
     self.PIPE = real_subprocess.PIPE
 
   def Popen(self, *args, **kwargs):
     assert self.Popen_hook or self.Popen_result
     if self.Popen_hook:
       return self.Popen_hook(*args, **kwargs)
     else:
       return self.Popen_result