Mac: Include Radeon 4670 in overlay blacklist

gpu/config/gpu_driver_bug_list_json.cc

 // Copyright (c) 2013 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.
 
 // Determines whether a certain driver bug exists in the current system.
 // The format of a valid gpu_driver_bug_list.json file is defined in
 // <gpu/config/gpu_control_list_format.txt>.
 // The supported "features" can be found in
 // <gpu/config/gpu_driver_bug_workaround_type.h>.
 
@@ skipping 1573 matching lines @@
       ]
     },
     {
       "id": 135,
       "description": "Screen flickers on 2009 iMacs",
       "cr_bugs": [543324],
       "os": {
         "type": "macosx"
       },
       "vendor_id": "0x1002",
-      "device_id": ["0x9440", "0x944a"],
+      "device_id": ["0x9440", "0x944a", "0x9488", "0x9490"],
       "features": [
         "disable_overlay_ca_layers",
         "disable_post_sub_buffers_for_onscreen_surfaces"
       ]
     }
   ]
 }
 
 );  // LONG_STRING_CONST macro
 
 }  // namespace gpu