Use macros to define pepper interfaces

ppapi/proxy/ppb_url_util_proxy.h

Index: ppapi/proxy/ppb_url_util_proxy.h
diff --git a/ppapi/proxy/ppb_url_util_proxy.h b/ppapi/proxy/ppb_url_util_proxy.h
index 2c6cb402f5526a4acfa020da5dec39023d78da4a..057137764674f63ca5ab55edc94a00d1b9055d45 100644
--- a/ppapi/proxy/ppb_url_util_proxy.h
+++ b/ppapi/proxy/ppb_url_util_proxy.h
@@ -16,15 +16,11 @@ namespace proxy {
 
 class PPB_URLUtil_Proxy : public InterfaceProxy {
  public:
-  PPB_URLUtil_Proxy(Dispatcher* dispatcher, const void* target_interface);
+  PPB_URLUtil_Proxy(Dispatcher* dispatcher);
   virtual ~PPB_URLUtil_Proxy();
 
   static const Info* GetInfo();
 
-  const PPB_URLUtil_Dev* ppb_url_util_target() const {
-    return static_cast<const PPB_URLUtil_Dev*>(target_interface());
-  }
-
   // InterfaceProxy implementation.
   virtual bool OnMessageReceived(const IPC::Message& msg);
 
@@ -44,6 +40,11 @@ class PPB_URLUtil_Proxy : public InterfaceProxy {
   void OnMsgGetPluginInstanceURL(PP_Instance instance,
                                  SerializedVarReturnValue result);
 
+  // When this proxy is in the host side, this value caches the interface
+  // pointer so we don't have to retrieve it from the dispatcher each time.
+  // In the plugin, this value is always NULL.
+  const PPB_URLUtil_Dev* ppb_url_util_impl_;
+
   DISALLOW_COPY_AND_ASSIGN(PPB_URLUtil_Proxy);
 };