cros: Change max users to be a constant

ash/public/interfaces/session_controller.mojom

 // Copyright 2016 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.
 
 module ash.mojom;
 
 import "components/signin/public/interfaces/account_id.mojom";
 import "skia/public/interfaces/bitmap.mojom";
 
 // Matches session_manager::SessionState.
@@ skipping 79 matching lines @@
 
   // Disallowed due to no eligible users.
   ERROR_NO_ELIGIBLE_USERS,
 
   // Disallowed due to reaching maximum supported user.
   ERROR_MAXIMUM_USERS_REACHED,
 };
 
 // Info about an ash session.
 struct SessionInfo {
-  // Maximum possible number of logged in users in ash.
-  uint32 max_users;
-
   // Whether the screen can be locked.
   bool can_lock_screen;
 
   // Whether the screen should be locked automatically before suspending.
   bool should_lock_screen_automatically;
 
   // Sets whether adding a user session to ash is allowed.
   AddUserSessionPolicy add_user_session_policy;
 
   // Current state of the ash session.
@@ skipping 25 matching lines @@
   // Requests to lock screen.
   RequestLockScreen();
 
   // Switch to the active user with |account_id| (if the user has already signed
   // in).
   SwitchActiveUser(signin.mojom.AccountId account_id);
 
   // Switch the active user to the next or previous user.
   CycleActiveUser(bool next_user);
 };