Remove gpu bots from sub-directory PRESUBMITs.

cc/PRESUBMIT.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.
 
 """Top-level presubmit script for cc.
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details about the presubmit API built into depot_tools.
 """
 
@@ skipping 355 matching lines @@
   results += FindUselessIfdefs(input_api, output_api)
   results += CheckOverrideFinal(input_api, output_api)
   results += input_api.canned_checks.CheckPatchFormatted(input_api, output_api)
   return results
 
 def GetPreferredTryMasters(project, change):
   return {
     'tryserver.blink': {
       'linux_blink_rel': set(['defaulttests']),
     },
-    'tryserver.chromium.gpu': {
-      'linux_gpu': set(['defaulttests']),
-      'mac_gpu': set(['defaulttests']),
-      'win_gpu': set(['defaulttests']),
-    },
   }