cros: Disable system tray help/lock buttons during supervised user creation

ash/system/tray_accessibility.h

 // Copyright (c) 2012 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_SYSTEM_TRAY_ACCESSIBILITY_H_
 #define ASH_SYSTEM_TRAY_ACCESSIBILITY_H_
 
 #include <stdint.h>
 
 #include "ash/accessibility_delegate.h"
@@ skipping 45 matching lines @@
 
   views::Label* label_;
 
   DISALLOW_COPY_AND_ASSIGN(AccessibilityPopupView);
 };
 
 // Create the detailed view of accessibility tray.
 class AccessibilityDetailedView : public TrayDetailsView,
                                   public ShellObserver {
  public:
-  AccessibilityDetailedView(SystemTrayItem* owner, LoginStatus login);
+  explicit AccessibilityDetailedView(SystemTrayItem* owner);
   ~AccessibilityDetailedView() override {}
 
  private:
   // TrayDetailsView:
   void HandleViewClicked(views::View* view) override;
   void HandleButtonPressed(views::Button* sender,
                            const ui::Event& event) override;
   void CreateExtraTitleRowButtons() override;
 
   // Launches the WebUI settings in a browser and closes the system menu.
@@ skipping 87 matching lines @@
   // A11y feature status on just entering the lock screen.
   bool show_a11y_menu_on_lock_screen_;
 
   friend class chromeos::TrayAccessibilityTest;
   DISALLOW_COPY_AND_ASSIGN(TrayAccessibility);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_TRAY_ACCESSIBILITY_H_