Converts DockedWindowLayoutManager to use WmRootWindowControllerObserver

ash/wm/common/wm_root_window_controller.h

 // 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.
 
 #ifndef ASH_WM_COMMON_WM_ROOT_CONTROLLER_H_
 #define ASH_WM_COMMON_WM_ROOT_CONTROLLER_H_
 
 #include <stdint.h>
 
 #include "ash/ash_export.h"
 #include "ash/wm/common/workspace/workspace_types.h"
 #include "ui/views/widget/widget.h"
 
 namespace ash {
 namespace wm {
 
 class WmGlobals;
+class WmRootWindowControllerObserver;
 class WmWindow;
 
 // Provides state associated with a root of a window hierarchy.
 class ASH_EXPORT WmRootWindowController {
  public:
   virtual ~WmRootWindowController() {}
 
   static WmRootWindowController* GetWithDisplayId(int64_t id);
 
   virtual bool HasShelf() = 0;
 
   virtual WmGlobals* GetGlobals() = 0;
 
   virtual WorkspaceWindowState GetWorkspaceWindowState() = 0;
 
   // Returns the window associated with this WmRootWindowController.
   virtual WmWindow* GetWindow() = 0;
 
   // Configures |init_params| prior to initializing |widget|.
   // |shell_container_id| is the id of the container to parent |widget| to.
   virtual void ConfigureWidgetInitParamsForContainer(
       views::Widget* widget,
       int shell_container_id,
       views::Widget::InitParams* init_params) = 0;
+
+  virtual void AddObserver(WmRootWindowControllerObserver* observer) = 0;
+  virtual void RemoveObserver(WmRootWindowControllerObserver* observer) = 0;
 };
 
 }  // namespace wm
 }  // namespace ash
 
 #endif  // ASH_WM_COMMON_WM_ROOT_CONTROLLER_H_