cros: Use SessionController to enable system tray settings / notifications tray

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 "ui/gfx/image/mojo/image.mojom";
 
 // Matches session_manager::SessionState.
@@ skipping 66 matching lines @@
   // (chrome) when a user session starts and never changes during the lifetime
   // of the session manager. The number starts at 1 for the first user session
   // and incremented by one for each subsequent user session.
   uint32 session_id;
 
   UserType type;
   signin.mojom.AccountId account_id;
   string display_name;
   string display_email;
   gfx.mojom.ImageSkia avatar;
+
+  // Whether the settings icon should be enabled in the system tray menu.
+  // Usually true after login, but can be false for specialized user sessions
+  // (e.g. adding supervised users).
+  bool should_enable_settings;
+
+  // Similar to |should_show_settings| but for the notification tray.
+  bool should_show_notification_tray;
 };
 
 // Matches ash::AddUserSessionPolicy.
 enum AddUserSessionPolicy {
   // Adding a user session is allowed.
   ALLOWED,
 
   // Disallowed due to primary user's policy.
   ERROR_NOT_ALLOWED_PRIMARY_USER,
 
@@ skipping 49 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(CycleUserDirection direction);
 };