Convert resources to take an instance key instead of an Instance*.

ppapi/cpp/private/flash_menu.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 PPAPI_CPP_PRIVATE_FLASH_MENU_H_
 #define PPAPI_CPP_PRIVATE_FLASH_MENU_H_
 
 #include "ppapi/c/private/ppb_flash_menu.h"
 #include "ppapi/cpp/resource.h"
 
 namespace pp {
 
 class CompletionCallback;
-class Instance;
+class InstanceHandle;
 class Point;
 
 namespace flash {
 
 class Menu : public Resource {
  public:
   // TODO(viettrungluu): Write a proper C++ wrapper of |PP_Flash_Menu|.
-  Menu(const Instance& instance, const struct PP_Flash_Menu* menu_data);
+  Menu(const InstanceHandle& instance, const struct PP_Flash_Menu* menu_data);
 
   int32_t Show(const Point& location,
                int32_t* selected_id,
                const CompletionCallback& cc);
 };
 
 }  // namespace flash
 }  // namespace pp
 
 #endif  // PPAPI_CPP_PRIVATE_FLASH_H_