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

ui/base/keycodes/keyboard_codes_posix.h

Index: ui/base/keycodes/keyboard_codes_posix.h
diff --git a/ui/base/keycodes/keyboard_codes_posix.h b/ui/base/keycodes/keyboard_codes_posix.h
index c9757b82baf2c72f1b1fccdf74412b1b74d5b270..5534cc4bc89a61a4f56ed9ab34a6fc0aa3e820d6 100644
--- a/ui/base/keycodes/keyboard_codes_posix.h
+++ b/ui/base/keycodes/keyboard_codes_posix.h
@@ -204,7 +204,12 @@ typedef enum {
   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