Delete widget tree (FrameView::parent_)

third_party/WebKit/Source/core/frame/FrameOrPlugin.h

 // Copyright 2017 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 FrameOrPlugin_h
 #define FrameOrPlugin_h
 
 #include "core/CoreExport.h"
 #include "platform/heap/Handle.h"
 
 namespace blink {
 
 class CullRect;
 class FrameView;
 class GraphicsContext;
 class IntRect;
 
 // FrameOrPlugin is a pure virtual class which is implemented by FrameView,
 // RemoteFrameView, and PluginView.
 class CORE_EXPORT FrameOrPlugin : public GarbageCollectedMixin {
  public:
   virtual ~FrameOrPlugin() {}
 
   virtual bool IsFrameView() const { return false; }
   virtual bool IsPluginView() const { return false; }
 
   virtual void SetParent(FrameView*) = 0;
   virtual FrameView* Parent() const = 0;
+  enum FrameOrPluginState { kNotAttached, kAttached, kDeferred, kDisposed };
+  virtual void SetFrameOrPluginState(FrameOrPluginState) = 0;
+  virtual FrameOrPluginState GetFrameOrPluginState() const = 0;
   virtual void SetParentVisible(bool) = 0;
   virtual void SetFrameRect(const IntRect&) = 0;
   virtual void FrameRectsChanged() = 0;
   virtual const IntRect& FrameRect() const = 0;
   virtual void Paint(GraphicsContext&, const CullRect&) const = 0;
   virtual void Show() = 0;
   virtual void Hide() = 0;
   virtual void Dispose() = 0;
 };
 
 }  // namespace blink
 #endif  // FrameOrPlugin_h