ash: Reorder shutdown of ShelfLayoutManager and StatusAreaWidget

ash/wm/aura/wm_shelf_aura.cc

 // 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.
 
 #include "ash/wm/aura/wm_shelf_aura.h"
 
 #include "ash/shelf/shelf.h"
 #include "ash/shelf/shelf_layout_manager.h"
 #include "ash/wm/aura/wm_window_aura.h"
 #include "ash/wm/common/shelf/wm_shelf_observer.h"
@@ skipping 52 matching lines @@
 }
 
 void WmShelfAura::AddObserver(WmShelfObserver* observer) {
   observers_.AddObserver(observer);
 }
 
 void WmShelfAura::RemoveObserver(WmShelfObserver* observer) {
   observers_.RemoveObserver(observer);
 }
 
-void WmShelfAura::WillDeleteShelf() {
+void WmShelfAura::WillDeleteShelfLayoutManager() {
   shelf_layout_manager_->RemoveObserver(this);
   shelf_layout_manager_ = nullptr;
 }
 
 void WmShelfAura::OnBackgroundUpdated(
     wm::ShelfBackgroundType background_type,
     BackgroundAnimatorChangeType change_type) {
   FOR_EACH_OBSERVER(WmShelfObserver, observers_,
                     OnBackgroundUpdated(background_type, change_type));
 }
 
 void WmShelfAura::WillChangeVisibilityState(ShelfVisibilityState new_state) {
   FOR_EACH_OBSERVER(WmShelfObserver, observers_,
                     WillChangeVisibilityState(new_state));
 }
 
 void WmShelfAura::OnShelfIconPositionsChanged() {
   FOR_EACH_OBSERVER(WmShelfObserver, observers_, OnShelfIconPositionsChanged());
 }
 
 }  // namespace wm
 }  // namespace ash