Attempting to fix problems in 11571014.

chrome/renderer/extensions/native_handler.h

 // Copyright (c) 2012 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 CHROME_RENDERER_EXTENSIONS_NATIVE_HANDLER_H_
 #define CHROME_RENDERER_EXTENSIONS_NATIVE_HANDLER_H_
 
 #include "v8/include/v8.h"
 
 namespace extensions {
 
 // NativeHandlers are intended to be used with a ModuleSystem. The ModuleSystem
 // will assume ownership of the NativeHandler, and as a ModuleSystem is tied to
 // a single v8::Context, this implies that NativeHandlers will also be tied to
 // a single v8::Context.
 // TODO(koz): Rename this to NativeJavaScriptModule.
 class NativeHandler {
  public:
-  virtual ~NativeHandler() {}
+  NativeHandler();
+  virtual ~NativeHandler();
 
   // Create a new instance of the object this handler specifies.
   virtual v8::Handle<v8::Object> NewInstance() = 0;
+
+  // Invalidate this object so it cannot be used any more. This is needed
+  // because it's possible for this to outlive its owner context. Invalidate
+  // must be called before this happens.
+  //
+  // Subclasses should override to invalidate their own V8 state. If they do
+  // they must call their superclass' Invalidate().
+  virtual void Invalidate();
+
+ protected:
+  // Allow subclasses to query valid state.
+  bool is_valid() { return is_valid_; }
+
+ private:
+  bool is_valid_;
 };
 
 }  // extensions
 
 #endif  // CHROME_RENDERER_EXTENSIONS_NATIVE_HANDLER_H_