Use macros to define pepper interfaces

ppapi/proxy/ppp_graphics_3d_proxy.h

Index: ppapi/proxy/ppp_graphics_3d_proxy.h
diff --git a/ppapi/proxy/ppp_graphics_3d_proxy.h b/ppapi/proxy/ppp_graphics_3d_proxy.h
index eb3d3b06aa2e1ff52f92ea2a4f2f3d1aaf32c7df..e3404245cd01e761821537acd07eef1e07f1f0f2 100644
--- a/ppapi/proxy/ppp_graphics_3d_proxy.h
+++ b/ppapi/proxy/ppp_graphics_3d_proxy.h
@@ -16,21 +16,24 @@ namespace proxy {
 
 class PPP_Graphics3D_Proxy : public InterfaceProxy {
  public:
-  PPP_Graphics3D_Proxy(Dispatcher* dispatcher, const void* target_interface);
+  PPP_Graphics3D_Proxy(Dispatcher* dispatcher);
   virtual ~PPP_Graphics3D_Proxy();
 
   static const Info* GetInfo();
 
-  const PPP_Graphics3D* ppp_graphics_3d_target() const {
-    return reinterpret_cast<const PPP_Graphics3D*>(target_interface());
-  }
-
   // InterfaceProxy implementation.
   virtual bool OnMessageReceived(const IPC::Message& msg);
 
  private:
   // Message handlers.
   void OnMsgContextLost(PP_Instance instance);
+
+  // 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_Graphics3D* ppp_graphics_3d_impl_;
+
+  DISALLOW_COPY_AND_ASSIGN(PPP_Graphics3D_Proxy);
 };
 
 }  // namespace proxy