Marks KeyboardCode as extensible

components/mus/public/interfaces/input_key_codes.mojom

 // Copyright 2014 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.
 
 module mus.mojom;
 
 // Cross platform keyboard codes.
 //
 // Because the web has standardized on Win32 keyboard codes, so does mojo.
+// TODO: shouldn't need extensible, see http://crbug.com/582279
+[Extensible=True]
 enum KeyboardCode {
   BACK                      = 0x08,
   TAB                       = 0x09,
   CLEAR                     = 0x0C,
   RETURN                    = 0x0D,
   SHIFT                     = 0x10,
   CONTROL                   = 0x11,
   MENU                      = 0x12,  // a.k.a. ALT
   PAUSE                     = 0x13,
   CAPITAL                   = 0x14,
@@ skipping 157 matching lines @@
   ZOOM                      = 0xFB,
   NONAME                    = 0xFC,
   PA1                       = 0xFD,
   OEM_CLEAR                 = 0xFE,
   UNKNOWN                   = 0,
 
   // Windows does not have a specific key code for AltGr. We use the unused
   // VK_OEM_AX to represent AltGr, matching the behaviour of Firefox on Linux.
   ALTGR                     = 0xE1,
 };