Revert 153092 - Turn on warnings as errors for (most) third_party code on Windows

third_party/mesa/mesa.gyp

 # 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.
 
 {
   'variables': {
-    # Disable warnings as errors for mesa until they're fixed or disabled.
-    # http://crbug.com/143877
-    'win_third_party_warn_as_error': 'false',
   },
   'target_defaults': {
     'conditions': [
       ['OS!="win"', {
         'defines': [
           # For talloc
           'HAVE_VA_COPY',
         ],
       }],
       ['OS!="mac"', {
@@ skipping 545 matching lines @@
         'MesaLib/src/mesa/drivers/common/driverfuncs.c',
         'MesaLib/src/mesa/drivers/common/driverfuncs.h',
         'MesaLib/src/mesa/drivers/common/meta.c',
         'MesaLib/src/mesa/drivers/common/meta.h',
         'MesaLib/src/mesa/drivers/osmesa/osmesa.c',
         'MesaLib/src/mesa/drivers/osmesa/osmesa.def',
       ],
     },
   ],
 }