Use macros to define pepper interfaces

ppapi/proxy/ppb_audio_proxy.h

Index: ppapi/proxy/ppb_audio_proxy.h
diff --git a/ppapi/proxy/ppb_audio_proxy.h b/ppapi/proxy/ppb_audio_proxy.h
index 7948b9cb8804116a14cb9de97caf0592088c3f35..b548e7237e5ba3d2ec6d031cb9c5a34d7fc4386c 100644
--- a/ppapi/proxy/ppb_audio_proxy.h
+++ b/ppapi/proxy/ppb_audio_proxy.h
@@ -30,11 +30,9 @@ namespace proxy {
 
 class PPB_Audio_Proxy : public InterfaceProxy {
  public:
-  PPB_Audio_Proxy(Dispatcher* dispatcher, const void* target_interface);
+  PPB_Audio_Proxy(Dispatcher* dispatcher);
   virtual ~PPB_Audio_Proxy();
 
-  static const Info* GetInfo();
-
   // Creates an Audio object in the plugin process.
   static PP_Resource CreateProxyResource(PP_Instance instance_id,
                                          PP_Resource config_id,
@@ -42,13 +40,11 @@ class PPB_Audio_Proxy : public InterfaceProxy {
                                          void* user_data);
 
 
-  const PPB_Audio* ppb_audio_target() const {
-    return static_cast<const PPB_Audio*>(target_interface());
-  }
-
   // InterfaceProxy implementation.
   virtual bool OnMessageReceived(const IPC::Message& msg);
 
+  static const InterfaceID kInterfaceID = INTERFACE_ID_PPB_AUDIO;
+
  private:
   // Plugin->renderer message handlers.
   void OnMsgCreate(PP_Instance instance_id,