Add a very basic PIN UI implementation that is shared between lock and settings.

chrome/browser/ui/webui/chromeos/login/signin_screen_handler.h

 // Copyright (c) 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.
 
 #ifndef CHROME_BROWSER_UI_WEBUI_CHROMEOS_LOGIN_SIGNIN_SCREEN_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_CHROMEOS_LOGIN_SIGNIN_SCREEN_HANDLER_H_
 
 #include <map>
 #include <memory>
 #include <set>
@@ skipping 307 matching lines @@
 
   void UpdateAddButtonStatus();
 
   // Restore input focus to current user pod.
   void RefocusCurrentPod();
 
   // WebUI message handlers.
   void HandleGetUsers();
   void HandleAuthenticateUser(const AccountId& account_id,
                               const std::string& password);
+  void HandleAuthenticateUserWithPin(const AccountId& account_id,
+                                     const std::string& password);
   void HandleAttemptUnlock(const std::string& username);
   void HandleLaunchIncognito();
   void HandleLaunchPublicSession(const AccountId& account_id,
                                  const std::string& locale,
                                  const std::string& input_method);
   void HandleOfflineLogin(const base::ListValue* args);
   void HandleShutdownSystem();
   void HandleLoadWallpaper(const AccountId& account_id);
   void HandleRebootSystem();
   void HandleRemoveUser(const AccountId& account_id);
@@ skipping 148 matching lines @@
   std::unique_ptr<LoginFeedback> login_feedback_;
 
   base::WeakPtrFactory<SigninScreenHandler> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(SigninScreenHandler);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_UI_WEBUI_CHROMEOS_LOGIN_SIGNIN_SCREEN_HANDLER_H_