mash: Avoid shelf crashes on display removal.

ash/common/shelf/shelf_widget.cc

 // Copyright 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.
 
 #include "ash/common/shelf/shelf_widget.h"
 
 #include "ash/common/focus_cycler.h"
 #include "ash/common/material_design/material_design_controller.h"
 #include "ash/common/session/session_state_delegate.h"
 #include "ash/common/shelf/shelf_background_animator_observer.h"
@@ skipping 479 matching lines @@
   // access it later in shutdown.
   if (shelf_layout_manager_)
     shelf_layout_manager_->PrepareForShutdown();
 
   if (status_area_widget_) {
     background_animator_.RemoveObserver(status_area_widget_);
     WmShell::Get()->focus_cycler()->RemoveWidget(status_area_widget_);
     status_area_widget_->Shutdown();
     status_area_widget_ = nullptr;
   }
+
+  CloseNow();
 }
 
 void ShelfWidget::ForceUndimming(bool force) {
   delegate_view_->ForceUndimming(force);
 }
 
 void ShelfWidget::UpdateIconPositionForPanel(WmWindow* panel) {
   WmWindow* shelf_window = WmLookup::Get()->GetWindowForWidget(this);
   shelf_view_->UpdatePanelIconPosition(
       panel->GetIntProperty(WmWindowProperty::SHELF_ID),
@@ skipping 50 matching lines @@
   if (shelf_view_)
     shelf_view_->UpdateShelfItemBackground(alpha);
 }
 
 void ShelfWidget::WillDeleteShelfLayoutManager() {
   shelf_layout_manager_->RemoveObserver(this);
   shelf_layout_manager_ = nullptr;
 }
 
 }  // namespace ash