cros: Implement cryptohome backend for pin.

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 349 matching lines @@
   // lock_screen_apps::StateObserver:
   void OnLockScreenNoteStateChanged(ash::mojom::TrayActionState state) override;
 
   void UpdateAddButtonStatus();
 
   // Restore input focus to current user pod.
   void RefocusCurrentPod();
 
   // Enable or disable the pin keyboard for the given account.
   void UpdatePinKeyboardState(const AccountId& account_id);
+  void UpdatePinKeyboardStateCallback(const AccountId& account_id,
+                                      bool is_enabled);
+  // Callback run by PinBackend. If |should_enabled| is true the PIN keyboard is
+  // preloaded.
+  void PreloadPinKeyboardCallback(bool should_enabled);
 
   // WebUI message handlers.
   void HandleGetUsers();
   void HandleAuthenticateUser(const AccountId& account_id,
                               const std::string& password,
                               bool authenticated_by_pin);
   void HandleAttemptUnlock(const std::string& username);
   void HandleLaunchIncognito();
   void HandleLaunchPublicSession(const AccountId& account_id,
                                  const std::string& locale,
@@ skipping 178 matching lines @@
       lock_screen_apps_observer_;
 
   base::WeakPtrFactory<SigninScreenHandler> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(SigninScreenHandler);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_UI_WEBUI_CHROMEOS_LOGIN_SIGNIN_SCREEN_HANDLER_H_