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

chrome/browser/chromeos/login/lock/screen_locker.h

Index: chrome/browser/chromeos/login/lock/screen_locker.h
diff --git a/chrome/browser/chromeos/login/lock/screen_locker.h b/chrome/browser/chromeos/login/lock/screen_locker.h
index dba07eb44bdd26fa11b408c417e09a9f89f03d63..558c018d7cabccdbf36250a7c862c70c20c596d1 100644
--- a/chrome/browser/chromeos/login/lock/screen_locker.h
+++ b/chrome/browser/chromeos/login/lock/screen_locker.h
@@ -101,6 +101,8 @@ class ScreenLocker : public AuthStatusConsumer,
     DISALLOW_COPY_AND_ASSIGN(Delegate);
   };
 
+  using AuthenticateCallback = base::OnceCallback<void(bool auth_success)>;
+
   explicit ScreenLocker(const user_manager::UserList& users);
 
   // Returns the default instance if it has been created.
@@ -126,7 +128,8 @@ class ScreenLocker : public AuthStatusConsumer,
   void UnlockOnLoginSuccess();
 
   // Authenticates the user with given |user_context|.
-  void Authenticate(const UserContext& user_context);
+  void Authenticate(const UserContext& user_context,
+                    AuthenticateCallback callback);
 
   // Close message bubble to clear error messages.
   void ClearErrors();
@@ -268,6 +271,9 @@ class ScreenLocker : public AuthStatusConsumer,
   // Type of the last unlock attempt.
   UnlockType unlock_attempt_type_ = AUTH_PASSWORD;
 
+  // Callback to run, if any, when authentication is done.
+  AuthenticateCallback on_auth_complete_;
+
   // Copy of parameters passed to last call of OnLoginSuccess for usage in
   // UnlockOnLoginSuccess().
   std::unique_ptr<AuthenticationParametersCapture> authentication_capture_;