PRESUBMIT: Enable header guard checks for cpplint.

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 50 matching lines @@
   depot_tools/presubmit_canned_checks.py but has less filters and only checks
   added files."""
   result = []
 
   # Initialize cpplint.
   import cpplint
   # Access to a protected member _XX of a client class
   # pylint: disable=W0212
   cpplint._cpplint_state.ResetErrorCounts()
 
-  # Justifications for each filter:
-  #
-  # - build/header_guard  : WebRTC coding style says they should be prefixed
-  #                         with WEBRTC_, which is not possible to configure in
-  #                         cpplint.py.
-  cpplint._SetFilters('-build/header_guard')
-
   # Use the strictest verbosity level for cpplint.py (level 1) which is the
   # default when running cpplint.py from command line.
   # To make it possible to work with not-yet-converted code, we're only applying
   # it to new (or moved/renamed) files and files listed in LINT_FOLDERS.
   verbosity_level = 1
   files = []
   for f in input_api.AffectedSourceFiles(source_file_filter):
     # Note that moved/renamed files also count as added.
     if f.Action() == 'A':
       files.append(f.AbsoluteLocalPath())
@@ skipping 268 matching lines @@
     for builder in masters[master]:
       if 'presubmit' in builder:
         # Do not trigger presubmit builders, since they're likely to fail
         # (e.g. OWNERS checks before finished code review), and we're running
         # local presubmit anyway.
         pass
       else:
         try_config[master][builder] = ['defaulttests']
 
   return try_config