mash: Add WmShell::SetDisplayWorkAreaInsets for ShelfLayoutManager.

ash/shelf/shelf_layout_manager.h

 // 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.
 
 #ifndef ASH_SHELF_SHELF_LAYOUT_MANAGER_H_
 #define ASH_SHELF_SHELF_LAYOUT_MANAGER_H_
 
 #include <memory>
 
 #include "ash/ash_export.h"
@@ skipping 283 matching lines @@
   // Returns true if there is a fullscreen window open that causes the shelf
   // to be hidden.
   bool IsShelfHiddenForFullscreen() const;
 
   // Gesture related functions:
   void StartGestureDrag(const ui::GestureEvent& gesture);
   void UpdateGestureDrag(const ui::GestureEvent& gesture);
   void CompleteGestureDrag(const ui::GestureEvent& gesture);
   void CancelGestureDrag();
 
-  // The RootWindow is cached so that we don't invoke Shell::GetInstance() from
-  // our destructor. We avoid that as at the time we're deleted Shell is being
-  // deleted too.
-  aura::Window* root_window_;
-
   // True when inside UpdateBoundsAndOpacity() method. Used to prevent calling
   // UpdateBoundsAndOpacity() again from SetChildBounds().
   bool updating_bounds_;
 
   bool in_shutdown_ = false;
 
   // Current state.
   State state_;
 
   ShelfWidget* shelf_widget_;
@@ skipping 59 matching lines @@
 
   std::unique_ptr<RootWindowControllerObserverImpl>
       root_window_controller_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(ShelfLayoutManager);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SHELF_SHELF_LAYOUT_MANAGER_H_