[Cronet] run pylint in Cronet presubmit check

components/cronet/PRESUBMIT.py

 # Copyright 2015 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.
 
 """Top-level presubmit script for src/components/cronet.
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details about the presubmit API built into depot_tools.
 """
 
+def _PyLintChecks(input_api, output_api):
+  pylint_checks = input_api.canned_checks.GetPylint(input_api, output_api,
+          extra_paths_list=_GetPathsToPrepend(input_api), pylintrc='pylintrc')
+  return input_api.RunTests(pylint_checks)
+
+def _GetPathsToPrepend(input_api):
+  current_dir = input_api.PresubmitLocalPath()
+  chromium_src_dir = input_api.os_path.join(current_dir, '..', '..')
+  return [
+    input_api.os_path.join(current_dir, 'tools'),
+    input_api.os_path.join(current_dir, 'android', 'test', 'javaperftests'),
+    input_api.os_path.join(chromium_src_dir, 'tools', 'perf'),
+    input_api.os_path.join(chromium_src_dir, 'build', 'android'),
+    input_api.os_path.join(chromium_src_dir, 'build', 'android', 'gyp', 'util'),
+    input_api.os_path.join(chromium_src_dir, 'net', 'tools', 'net_docs'),
+    input_api.os_path.join(chromium_src_dir, 'tools'),
+    input_api.os_path.join(chromium_src_dir, 'third_party'),
+    input_api.os_path.join(chromium_src_dir,
+        'third_party', 'catapult', 'telemetry'),
+    input_api.os_path.join(chromium_src_dir,
+        'third_party', 'catapult', 'devil'),
+  ]
+
 def CheckChangeOnUpload(input_api, output_api):
-  return input_api.canned_checks.CheckPatchFormatted(input_api, output_api)
+  results = []
+  results.extend(_PyLintChecks(input_api, output_api))
+  results.extend(
+      input_api.canned_checks.CheckPatchFormatted(input_api, output_api))
+  return results