Fix Chrome crashes on calling OnTrayVisibilityChange

ash/common/system/status_area_widget.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_COMMON_SYSTEM_STATUS_AREA_WIDGET_H_
 #define ASH_COMMON_SYSTEM_STATUS_AREA_WIDGET_H_
 
 #include "ash/ash_export.h"
 #include "ash/common/login_status.h"
 #include "ash/common/shelf/shelf_background_animator_observer.h"
 #include "ash/public/cpp/shelf_types.h"
 #include "base/macros.h"
 #include "ui/views/widget/widget.h"
 
 namespace ash {
 class OverviewButtonTray;
 class StatusAreaWidgetDelegate;
 class SystemTray;
 class TrayBackgroundView;
 class WebNotificationTray;
 class WmShelf;
 class WmWindow;
 #if defined(OS_CHROMEOS)
 class ImeMenuTray;
 class LogoutButtonTray;
 class PaletteTray;
 class VirtualKeyboardTray;
 #endif
 
+namespace test {
+class SystemTrayTest;
+}
+
 class ASH_EXPORT StatusAreaWidget : public views::Widget,
                                     public ShelfBackgroundAnimatorObserver {
  public:
   StatusAreaWidget(WmWindow* status_container, WmShelf* wm_shelf);
   ~StatusAreaWidget() override;
 
   // Creates the SystemTray, WebNotificationTray and LogoutButtonTray.
   void CreateTrayViews();
 
   // Destroys the system tray and web notification tray. Called before
@@ skipping 46 matching lines @@
   void SchedulePaint();
 
   // Overridden from views::Widget:
   const ui::NativeTheme* GetNativeTheme() const override;
   void OnNativeWidgetActivationChanged(bool active) override;
 
   // ShelfBackgroundAnimatorObserver:
   void UpdateShelfItemBackground(int alpha) override;
 
  private:
+  friend class test::SystemTrayTest;
+
   void AddSystemTray();
   void AddWebNotificationTray();
 #if defined(OS_CHROMEOS)
   void AddLogoutButtonTray();
   void AddPaletteTray();
   void AddVirtualKeyboardTray();
   void AddImeMenuTray();
 
   // Checks if |tray| is the next visible tray to the left of
   // |logout_button_tray_|. Returns true if both are visible, false otherwise.
@@ skipping 15 matching lines @@
   LoginStatus login_status_;
 
   WmShelf* wm_shelf_;
 
   DISALLOW_COPY_AND_ASSIGN(StatusAreaWidget);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SYSTEM_STATUS_AREA_WIDGET_H_