cros: Make sure views-based lock screen is destroyed after it is dismissed.

ash/login/lock_screen_controller.h

 // Copyright 2017 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 ASH_LOGIN_LOCK_SCREEN_CONTROLLER_H_
 #define ASH_LOGIN_LOCK_SCREEN_CONTROLLER_H_
 
 #include "ash/ash_export.h"
 #include "ash/public/interfaces/lock_screen.mojom.h"
 #include "base/macros.h"
 #include "mojo/public/cpp/bindings/binding_set.h"
 
 namespace ash {
 
 // LockScreenController implements mojom::LockScreen and wraps the
 // mojom::LockScreenClient interface. This lets a consumer of ash provide a
 // LockScreenClient, which we will dispatch to if one has been provided to us.
 // This could send requests to LockScreenClient and also handle requests from
 // LockScreenClient through mojo.
 class ASH_EXPORT LockScreenController
     : NON_EXPORTED_BASE(public mojom::LockScreen) {
  public:
+  using OnShownCallback = base::OnceCallback<void(bool did_show)>;
+
   LockScreenController();
   ~LockScreenController() override;
 
   // Binds the mojom::LockScreen interface to this object.
   void BindRequest(mojom::LockScreenRequest request);
 
   // mojom::LockScreen:
   void SetClient(mojom::LockScreenClientPtr client) override;
+  void ShowLockScreen(ShowLockScreenCallback callback) override;
   void ShowErrorMessage(int32_t login_attempts,
                         const std::string& error_text,
                         const std::string& help_link_text,
                         int32_t help_topic_id) override;
   void ClearErrors() override;
 
   // Wrappers around the mojom::SystemTrayClient interface.
   // Hash the password and send AuthenticateUser request to LockScreenClient.
   // LockScreenClient(chrome) will do the authentication and request to show
   // error messages in the lock screen if auth fails, or request to clear
   // errors if auth succeeds.
-  void AuthenticateUser(const AccountId& account_id,
-                        const std::string& password,
-                        bool authenticated_by_pin);
+  void AuthenticateUser(
+      const AccountId& account_id,
+      const std::string& password,
+      bool authenticated_by_pin,
+      mojom::LockScreenClient::AuthenticateUserCallback callback);
 
  private:
-  void DoAuthenticateUser(const AccountId& account_id,
-                          const std::string& password,
-                          bool authenticated_by_pin,
-                          const std::string& system_salt);
+  using PendingAuthenticateUserCall =
+      base::OnceCallback<void(const std::string& system_salt)>;
+
+  void DoAuthenticateUser(
+      const AccountId& account_id,
+      const std::string& password,
+      bool authenticated_by_pin,
+      mojom::LockScreenClient::AuthenticateUserCallback callback,
+      const std::string& system_salt);
+
+  void OnGetSystemSalt(const std::string& system_salt);
 
   // Client interface in chrome browser. May be null in tests.
   mojom::LockScreenClientPtr lock_screen_client_;
 
   // Bindings for the LockScreen interface.
   mojo::BindingSet<mojom::LockScreen> bindings_;
 
+  // User authentication calls that will run when we have system salt.
+  std::vector<PendingAuthenticateUserCall> pending_user_auths_;
+
   DISALLOW_COPY_AND_ASSIGN(LockScreenController);
 };
 
-}  // namspace ash
+}  // namespace ash
 
 #endif  // ASH_LOGIN_LOCK_SCREEN_CONTROLLER_H_