Use macros to define pepper interfaces

ppapi/proxy/ppp_video_decoder_proxy.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_PROXY_PPP_VIDEO_DECODER_PROXY_H_
 #define PPAPI_PROXY_PPP_VIDEO_DECODER_PROXY_H_
 
 #include "ppapi/c/dev/ppp_video_decoder_dev.h"
 #include "ppapi/c/pp_instance.h"
 #include "ppapi/proxy/interface_proxy.h"
 #include "ppapi/shared_impl/host_resource.h"
 
 struct PP_Picture_Dev;
 struct PP_Size;
 
 namespace ppapi {
 namespace proxy {
 
 class PPP_VideoDecoder_Proxy : public InterfaceProxy {
  public:
-  PPP_VideoDecoder_Proxy(Dispatcher* dispatcher, const void* target_interface);
+  PPP_VideoDecoder_Proxy(Dispatcher* dispatcher);
   virtual ~PPP_VideoDecoder_Proxy();
 
   static const Info* GetInfo();
 
-  const PPP_VideoDecoder_Dev* ppp_video_decoder_target() const {
-    return static_cast<const PPP_VideoDecoder_Dev*>(target_interface());
-  }
-
   // InterfaceProxy implementation.
   virtual bool OnMessageReceived(const IPC::Message& msg);
 
  private:
   // Message handlers.
   void OnMsgProvidePictureBuffers(const ppapi::HostResource& decoder,
                                   uint32_t req_num_of_buffers,
                                   const PP_Size& dimensions);
   void OnMsgDismissPictureBuffer(const ppapi::HostResource& decoder,
                                  int32_t picture_id);
   void OnMsgPictureReady(const ppapi::HostResource& decoder,
                          const PP_Picture_Dev& picture_buffer);
   void OnMsgNotifyEndOfStream(const ppapi::HostResource& decoder);
   void OnMsgNotifyError(const ppapi::HostResource& decoder,
                         PP_VideoDecodeError_Dev error);
 
+  // When this proxy is in the plugin side, this value caches the interface
+  // pointer so we don't have to retrieve it from the dispatcher each time.
+  // In the host, this value is always NULL.
+  const PPP_VideoDecoder_Dev* ppp_video_decoder_impl_;
+
   DISALLOW_COPY_AND_ASSIGN(PPP_VideoDecoder_Proxy);
 };
 
 }  // namespace proxy
 }  // namespace ppapi
 
 #endif  // PPAPI_PROXY_PPP_VIDEO_DECODER_PROXY_H_