Removes aura dependencies from WindowPositioner

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 "ash/ash_export.h"
 
 namespace ash {
 namespace wm {
 
+class WmGlobals;
 class WmWindow;
 
 class ASH_EXPORT WmRootWindowController {
  public:
   virtual ~WmRootWindowController() {}
 
   virtual bool HasShelf() = 0;
+
+  virtual WmGlobals* GetGlobals() = 0;
 };
 
 }  // namespace wm
 }  // namespace ash
 
 #endif  // ASH_WM_COMMON_WM_ROOT_CONTROLLER_H_