Handle F6 and F7 (brightness keys) in ash [part 3 of 3].

ui/base/keycodes/keyboard_codes_posix.h

 // 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.
 
 /*
  * Copyright (C) 2006 Michael Emmel mike.emmel@gmail.com. All rights reserved.
  * Copyright (C) 2008, 2009 Google Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ skipping 186 matching lines @@
   VKEY_DBE_DBCSCHAR = 0xF4,
   VKEY_ATTN = 0xF6,
   VKEY_CRSEL = 0xF7,
   VKEY_EXSEL = 0xF8,
   VKEY_EREOF = 0xF9,
   VKEY_PLAY = 0xFA,
   VKEY_ZOOM = 0xFB,
   VKEY_NONAME = 0xFC,
   VKEY_PA1 = 0xFD,
   VKEY_OEM_CLEAR = 0xFE,
-  VKEY_UNKNOWN = 0
+  VKEY_UNKNOWN = 0,
+
+  // POSIX specific VKEYs. Note that as of Windows SDK 7.1, 0xD8-DA are
+  // unassigned.
+  VKEY_BRIGHTNESS_DOWN = 0xD8,
+  VKEY_BRIGHTNESS_UP = 0xD9
 } KeyboardCode;
 
 }  // namespace ui
 
 #endif  // UI_BASE_KEYCODES_KEYBOARD_CODES_POSIX_H_