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

ppapi/cpp/private/flash_clipboard.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 PPAPI_CPP_PRIVATE_FLASH_CLIPBOARD_H_
 #define PPAPI_CPP_PRIVATE_FLASH_CLIPBOARD_H_
 
 #include <string>
 
 #include "ppapi/c/private/ppb_flash_clipboard.h"
 
 namespace pp {
 
-class Instance;
+class InstanceHandle;
 
 namespace flash {
 
 class Clipboard {
  public:
   // Returns true if the required interface is available.
   static bool IsAvailable();
 
   // Returns true if the given format is available from the given clipboard.
-  static bool IsFormatAvailable(Instance* instance,
+  static bool IsFormatAvailable(const InstanceHandle& instance,
                                 PP_Flash_Clipboard_Type clipboard_type,
                                 PP_Flash_Clipboard_Format format);
 
   // Returns true on success, in which case |text_out| will be filled with plain
   // text read from the given clipboard.
-  static bool ReadPlainText(Instance* instance,
+  static bool ReadPlainText(const InstanceHandle& instance,
                             PP_Flash_Clipboard_Type clipboard_type,
                             std::string* text_out);
 
   // Returns true on success (it may fail if |text| is too big).
-  static bool WritePlainText(Instance* instance,
+  static bool WritePlainText(const InstanceHandle& instance,
                              PP_Flash_Clipboard_Type clipboard_type,
                              const std::string& text);
 };
 
 }  // namespace flash
 }  // namespace pp
 
 #endif  // PPAPI_CPP_PRIVATE_FLASH_CLIPBOARD_H_