Use macros to define pepper interfaces

ppapi/proxy/ppp_instance_private_proxy.h

Index: ppapi/proxy/ppp_instance_private_proxy.h
diff --git a/ppapi/proxy/ppp_instance_private_proxy.h b/ppapi/proxy/ppp_instance_private_proxy.h
index afab722975142e21cf2edbc03e15871f065180d3..1759eb920ffd8960340d492b0e7f42df76901048 100644
--- a/ppapi/proxy/ppp_instance_private_proxy.h
+++ b/ppapi/proxy/ppp_instance_private_proxy.h
@@ -20,16 +20,11 @@ class SerializedVarReturnValue;
 
 class PPP_Instance_Private_Proxy : public InterfaceProxy {
  public:
-  PPP_Instance_Private_Proxy(Dispatcher* dispatcher,
-                             const void* target_interface);
+  PPP_Instance_Private_Proxy(Dispatcher* dispatcher);
   virtual ~PPP_Instance_Private_Proxy();
 
   static const Info* GetInfo();
 
-  const PPP_Instance_Private* ppp_instance_private_target() const {
-    return reinterpret_cast<const PPP_Instance_Private*>(target_interface());
-  }
-
  private:
   // InterfaceProxy implementation.
   virtual bool OnMessageReceived(const IPC::Message& msg);
@@ -37,6 +32,13 @@ class PPP_Instance_Private_Proxy : public InterfaceProxy {
   // Message handlers.
   void OnMsgGetInstanceObject(PP_Instance instance,
                               SerializedVarReturnValue result);
+
+  // 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_Instance_Private* ppp_instance_private_impl_;
+
+  DISALLOW_COPY_AND_ASSIGN(PPP_Instance_Private_Proxy);
 };
 
 }  // namespace proxy