Refactor the way singleton-style resources are exposed via PPB_Instance

ppapi/thunk/ppb_flash_clipboard_api.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_THUNK_PPB_FLASH_CLIPBOARD_API_H_
 #define PPAPI_THUNK_PPB_FLASH_CLIPBOARD_API_H_
 
 #include "ppapi/c/private/ppb_flash_clipboard.h"
+#include "ppapi/shared_impl/singleton_resource_id.h"
 
 namespace ppapi {
 namespace thunk {
 
 class PPB_Flash_Clipboard_API {
  public:
   virtual ~PPB_Flash_Clipboard_API() {}
 
   // PPB_Flash_Clipboard.
-  virtual uint32_t RegisterCustomFormat(
-    PP_Instance instance,
-    const char* format_name) = 0;
-  virtual PP_Bool IsFormatAvailable(
-    PP_Instance instance,
-    PP_Flash_Clipboard_Type clipboard_type,
-    uint32_t format) = 0;
-  virtual PP_Var ReadData(
-    PP_Instance instance,
-    PP_Flash_Clipboard_Type clipboard_type,
-    uint32_t format) = 0;
-  virtual int32_t WriteData(
-    PP_Instance instance,
-    PP_Flash_Clipboard_Type clipboard_type,
-    uint32_t data_item_count,
-    const uint32_t formats[],
-    const PP_Var data_items[]) = 0;
+  virtual uint32_t RegisterCustomFormat(PP_Instance instance,
+                                        const char* format_name) = 0;
+  virtual PP_Bool IsFormatAvailable(PP_Instance instance,
+                                    PP_Flash_Clipboard_Type clipboard_type,
+                                    uint32_t format) = 0;
+  virtual PP_Var ReadData(PP_Instance instance,
+                          PP_Flash_Clipboard_Type clipboard_type,
+                          uint32_t format) = 0;
+  virtual int32_t WriteData(PP_Instance instance,
+                            PP_Flash_Clipboard_Type clipboard_type,
+                            uint32_t data_item_count,
+                            const uint32_t formats[],
+                            const PP_Var data_items[]) = 0;
+
+  static const SingletonResourceID kSingletonResourceID =
+      FLASH_CLIPBOARD_SINGLETON_ID;
 };
 
 }  // namespace thunk
 }  // namespace ppapi
 
 #endif // PPAPI_THUNK_PPB_FLASH_CLIPBOARD_API_H_