Use macros to define pepper interfaces

ppapi/proxy/ppp_messaging_proxy.h

Index: ppapi/proxy/ppp_messaging_proxy.h
diff --git a/ppapi/proxy/ppp_messaging_proxy.h b/ppapi/proxy/ppp_messaging_proxy.h
index 2deb40f60e52fd0d843248199e1487d42a055d38..bc898f31c320b623ee0ee5e635002ca48889fb1c 100644
--- a/ppapi/proxy/ppp_messaging_proxy.h
+++ b/ppapi/proxy/ppp_messaging_proxy.h
@@ -17,15 +17,11 @@ class SerializedVarReceiveInput;
 
 class PPP_Messaging_Proxy : public InterfaceProxy {
  public:
-  PPP_Messaging_Proxy(Dispatcher* dispatcher, const void* target_interface);
+  PPP_Messaging_Proxy(Dispatcher* dispatcher);
   virtual ~PPP_Messaging_Proxy();
 
   static const Info* GetInfo();
 
-  const PPP_Messaging* ppp_messaging_target() const {
-    return static_cast<const PPP_Messaging*>(target_interface());
-  }
-
   // InterfaceProxy implementation.
   virtual bool OnMessageReceived(const IPC::Message& msg) OVERRIDE;
 
@@ -33,6 +29,13 @@ class PPP_Messaging_Proxy : public InterfaceProxy {
   // Message handlers.
   void OnMsgHandleMessage(PP_Instance instance,
                           SerializedVarReceiveInput data);
+
+  // 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_Messaging* ppp_messaging_impl_;
+
+  DISALLOW_COPY_AND_ASSIGN(PPP_Messaging_Proxy);
 };
 
 }  // namespace proxy