views: Forward declare "class View;" in layout_manager.h

views/layout/layout_manager.h

 // Copyright (c) 2011 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 VIEWS_LAYOUT_MANAGER_H_
 #define VIEWS_LAYOUT_MANAGER_H_
 #pragma once
 
-#include "views/view.h"
-
 namespace gfx {
 class Size;
 }
 
 namespace views {
 
+class View;
+
 /////////////////////////////////////////////////////////////////////////////
 //
 // LayoutManager interface
 //
 //   The LayoutManager interface provides methods to handle the sizing of
 //   the children of a View according to implementation-specific heuristics.
 //
 /////////////////////////////////////////////////////////////////////////////
 class LayoutManager {
  public:
@@ skipping 23 matching lines @@
   // Notification that a view has been added.
   virtual void ViewAdded(View* host, View* view);
 
   // Notification that a view has been removed.
   virtual void ViewRemoved(View* host, View* view);
 };
 
 }  // namespace views
 
 #endif // VIEWS_LAYOUT_MANAGER_H_