events: keycodes: Remove the stateless singleton instance of KeycodeConverter

ui/events/keycodes/keyboard_code_conversion_win.cc

 // Copyright (c) 2011 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/keycodes/keyboard_code_conversion_win.h"
 #include "ui/events/keycodes/dom4/keycode_converter.h"
 
 namespace ui {
 
 WORD WindowsKeyCodeForKeyboardCode(KeyboardCode keycode) {
   return static_cast<WORD>(keycode);
 }
 
 KeyboardCode KeyboardCodeForWindowsKeyCode(WORD keycode) {
   return static_cast<KeyboardCode>(keycode);
 }
 
 const char* CodeForWindowsScanCode(WORD scan_code) {
-  return KeycodeConverter::GetInstance()->NativeKeycodeToCode(
-      scan_code);
+  return ui::KeycodeConverter::NativeKeycodeToCode(scan_code);
 }
 
 }  // namespace ui