Use macros to define pepper interfaces

ppapi/proxy/ppp_class_proxy.h

Index: ppapi/proxy/ppp_class_proxy.h
diff --git a/ppapi/proxy/ppp_class_proxy.h b/ppapi/proxy/ppp_class_proxy.h
index ce93770f339781af879cac9f56e5b62cb27e4274..299c3ec6f94cc17d23ae91ce71b4d702829903aa 100644
--- a/ppapi/proxy/ppp_class_proxy.h
+++ b/ppapi/proxy/ppp_class_proxy.h
@@ -31,6 +31,10 @@ class PPP_Class_Proxy : public InterfaceProxy {
   PPP_Class_Proxy(Dispatcher* dispatcher);
   virtual ~PPP_Class_Proxy();
 
+  // Factory function used for registration (normal code can just use the
+  // constructor).
+  static InterfaceProxy* Create(Dispatcher* dispatcher);
+
   // Creates a proxied object in the browser process. This takes the browser's
   // PPB_Var_Deprecated interface to use to create the object. The class and
   static PP_Var CreateProxiedObject(const PPB_Var_Deprecated* var,