Makes WorkspaceLayoutManager use ash/wm/common types

ash/wm/common/wm_window.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_WINDOW_H_
 #define ASH_WM_COMMON_WM_WINDOW_H_
 
 #include <memory>
 #include <vector>
 
@@ skipping 44 matching lines @@
   virtual WmRootWindowController* GetRootWindowController() = 0;
 
   // TODO(sky): fix constness.
   virtual WmGlobals* GetGlobals() const = 0;
 
   // Used for debugging.
   virtual void SetName(const std::string& name) = 0;
 
   // See wm_shell_window_ids.h for list of known ids.
   virtual void SetShellWindowId(int id) = 0;
-  virtual int GetShellWindowId() = 0;
+  virtual int GetShellWindowId() const = 0;
   virtual WmWindow* GetChildByShellWindowId(int id) = 0;
 
   virtual ui::wm::WindowType GetType() const = 0;
 
   // TODO(sky): seems like this shouldn't be exposed.
   virtual ui::Layer* GetLayer() = 0;
 
   virtual gfx::Display GetDisplayNearestWindow() = 0;
 
   virtual bool HasNonClientArea() = 0;
@@ skipping 125 matching lines @@
   virtual void RemoveObserver(WmWindowObserver* observer) = 0;
 
  protected:
   virtual ~WmWindow() {}
 };
 
 }  // namespace wm
 }  // namespace ash
 
 #endif  // ASH_WM_COMMON_WM_WINDOW_H_