Refactor the way singleton-style resources are exposed via PPB_Instance

ppapi/proxy/gamepad_resource.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_PROXY_GAMEPAD_RESOURCE_H_
 #define PPAPI_PROXY_GAMEPAD_RESOURCE_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 17 matching lines @@
 // perspective. But we need to make requests to the browser and get replies.
 // It's more convenient to do this as a resource, so the instance just
 // maintains an internal lazily instantiated copy of this resource.
 class PPAPI_PROXY_EXPORT GamepadResource
       : public PluginResource,
         public thunk::PPB_Gamepad_API {
  public:
   GamepadResource(Connection connection, PP_Instance instance);
   virtual ~GamepadResource();
 
+  // Resource implementation.
+  virtual thunk::PPB_Gamepad_API* AsPPB_Gamepad_API() OVERRIDE;
+
   // PPB_Gamepad_API.
   virtual void Sample(PP_GamepadsSampleData* data) OVERRIDE;
 
  private:
   void OnPluginMsgSendMemory(const ResourceMessageReplyParams& params);
 
   scoped_ptr<base::SharedMemory> shared_memory_;
   const ContentGamepadHardwareBuffer* buffer_;
 
   // Last data returned so we can use this in the event of a read failure.
   PP_GamepadsSampleData last_read_;
 
   DISALLOW_COPY_AND_ASSIGN(GamepadResource);
 };
 
 }  // namespace proxy
 }  // namespace ppapi
 
 #endif  // PPAPI_PROXY_GAMEPAD_RESOURCE_H_