mash: Move session_types.h to ash/public

ash/common/session/session_types.h

-// Copyright 2015 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_COMMON_SESSION_SESSION_TYPES_H_
-#define ASH_COMMON_SESSION_SESSION_TYPES_H_
-
-namespace ash {
-
-// The index of the user profile to use. The list is always LRU sorted so that
-// index 0 is the currently active user.
-using UserIndex = int;
-
-// Represents possible user adding scenarios.
-enum class AddUserSessionPolicy {
-  // Adding a user is allowed.
-  ALLOWED,
-  // Disallowed due to primary user's policy.
-  ERROR_NOT_ALLOWED_PRIMARY_USER,
-  // Disallowed due to no eligible users.
-  ERROR_NO_ELIGIBLE_USERS,
-  // Disallowed due to reaching maximum supported user.
-  ERROR_MAXIMUM_USERS_REACHED,
-};
-
-}  // namespace ash
-
-#endif  // ASH_COMMON_SESSION_SESSION_TYPES_H_