[IME] Loads chromeos-xkb extension and add the extension based xkb keyboards in the chrome://settin…

chrome/browser/chromeos/input_method/input_method_engine.cc

 // Copyright 2013 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 "chrome/browser/chromeos/input_method/input_method_engine.h"
 
 #define XK_MISCELLANY
 #include <X11/keysymdef.h>
 #include <X11/X.h>
 #include <X11/Xlib.h>
@@ skipping 88 matching lines @@
     imm_id_ = extension_ime_util::GetInputMethodID(extension_id, engine_id);
   }
 
   input_view_url_ = input_view;
   descriptor_ = input_method::InputMethodDescriptor(
       imm_id_,
       engine_name,
       std::string(), // TODO(uekawa): Set short name.
       layouts,
       languages,
-      false,  // is_login_keyboard
+      extension_ime_util::IsKeyboardLayoutExtension(
+          imm_id_), // is_login_keyboard
       options_page,
       input_view);
 
   // TODO(komatsu): It is probably better to call AddInputMethodExtension
   // out of Initialize.
   manager->AddInputMethodExtension(imm_id_, this);
 }
 
 const input_method::InputMethodDescriptor& InputMethodEngine::GetDescriptor()
     const {
@@ skipping 511 matching lines @@
           // TODO(nona): Implement it.
           break;
       }
     }
   }
 
   // TODO(nona): Support item.children.
 }
 
 }  // namespace chromeos