Make lint errors fatal in presubmit and fix files in whitelisted paths

PRESUBMIT.py

 # Copyright (c) 2012 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.
 
 import json
 import os
@@ skipping 237 matching lines @@
   for f in input_api.AffectedSourceFiles(source_file_filter):
     # Note that moved/renamed files also count as added.
     if f.Action() == 'A' or _IsLintWhitelisted(whitelist_dirs, f.LocalPath()):
       files.append(f.AbsoluteLocalPath())
 
   for file_name in files:
     cpplint.ProcessFile(file_name, verbosity_level)
 
   if cpplint._cpplint_state.error_count > 0:
     if input_api.is_committing:
-      # TODO(kjellander): Change back to PresubmitError below when we're
-      # confident with the lint settings.
-      res_type = output_api.PresubmitPromptWarning
+      res_type = output_api.PresubmitError
     else:
       res_type = output_api.PresubmitPromptWarning
     result = [res_type('Changelist failed cpplint.py check.')]
 
   return result
 
 def _CheckNoSourcesAbove(input_api, gn_files, output_api):
   # Disallow referencing source files with paths above the GN file location.
   source_pattern = input_api.re.compile(r' +sources \+?= \[(.*?)\]',
                                         re.MULTILINE | re.DOTALL)
@@ skipping 290 matching lines @@
       input_api, output_api))
   results.extend(input_api.canned_checks.CheckChangeHasDescription(
       input_api, output_api))
   results.extend(_CheckChangeHasBugField(input_api, output_api))
   results.extend(input_api.canned_checks.CheckChangeHasTestField(
       input_api, output_api))
   results.extend(input_api.canned_checks.CheckTreeIsOpen(
       input_api, output_api,
       json_url='http://webrtc-status.appspot.com/current?format=json'))
   return results