Removed mac_optional_gpu_tests_rel from extra trybots in gpu/ and webgl/.

third_party/WebKit/Source/modules/webgl/PRESUBMIT.py

 # Copyright (c) 2016 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 gpu.
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details about the presubmit API built into depot_tools.
 """
 
 
 import re
 
 
 def PostUploadHook(cl, change, output_api):
     """git cl upload will call this hook after the issue is created/modified.
 
     This hook adds extra try bots list to the CL description in order to run
     extra GPU tests in addition to CQ try bots.
     """
     rietveld_obj = cl.RpcServer()
     issue = cl.issue
     description = rietveld_obj.get_description(issue)
     if re.search(r'^CQ_INCLUDE_TRYBOTS=.*', description, re.M | re.I):
         return []
 
     bots = [
         'tryserver.chromium.win:win_optional_gpu_tests_rel',
-        'tryserver.chromium.mac:mac_optional_gpu_tests_rel',
     ]
 
     results = []
     new_description = description
     new_description += '\nCQ_INCLUDE_TRYBOTS=%s' % ';'.join(bots)
     results.append(output_api.PresubmitNotifyResult(
         'Automatically added optional GPU tests to run on CQ.'))
 
     if new_description != description:
         rietveld_obj.update_description(issue, new_description)
 
     return results