Don't do XKB lookup for DomCode::NONE.

ui/events/ozone/layout/xkb/xkb_keyboard_layout_engine.cc

 // 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.
 
 #include "ui/events/ozone/layout/xkb/xkb_keyboard_layout_engine.h"
 
 #include <xkbcommon/xkbcommon-names.h>
 
 #include "base/bind.h"
 #include "base/location.h"
@@ skipping 732 matching lines @@
   // NOTIMPLEMENTED();
   return false;
 }
 
 bool XkbKeyboardLayoutEngine::Lookup(DomCode dom_code,
                                      int flags,
                                      DomKey* dom_key,
                                      base::char16* character,
                                      KeyboardCode* key_code,
                                      uint32* platform_keycode) const {
+  if (dom_code == DomCode::NONE)
+    return false;
   // Convert DOM physical key to XKB representation.
   xkb_keycode_t xkb_keycode = key_code_converter_.DomCodeToXkbKeyCode(dom_code);
   if (xkb_keycode == key_code_converter_.InvalidXkbKeyCode()) {
     LOG(ERROR) << "No XKB keycode for DomCode 0x" << std::hex
                << static_cast<int>(dom_code) << " '"
                << KeycodeConverter::DomCodeToCodeString(dom_code) << "'";
     return false;
   }
   xkb_mod_mask_t xkb_flags = EventFlagsToXkbFlags(flags);
   // Obtain keysym and character.
@@ skipping 193 matching lines @@
     if (close_index == std::string::npos)
       close_index = layout_name.size();
     *layout_variant = layout_name.substr(parentheses_index + 1,
                                          close_index - parentheses_index - 1);
   } else if (dash_index != std::string::npos) {
     *layout_id = layout_name.substr(0, dash_index);
     *layout_variant = layout_name.substr(dash_index + 1);
   }
 }
 }  // namespace ui