Use macros to define pepper interfaces

ppapi/proxy/ppb_pdf_proxy.h

Index: ppapi/proxy/ppb_pdf_proxy.h
diff --git a/ppapi/proxy/ppb_pdf_proxy.h b/ppapi/proxy/ppb_pdf_proxy.h
index 27ab6c4c68bc312ab497e9df58854c8fbd517589..7ad012d20b6c93e23c8629faf3b3c402e1eb2c1e 100644
--- a/ppapi/proxy/ppb_pdf_proxy.h
+++ b/ppapi/proxy/ppb_pdf_proxy.h
@@ -18,15 +18,11 @@ struct SerializedFontDescription;
 
 class PPB_PDF_Proxy : public InterfaceProxy {
  public:
-  PPB_PDF_Proxy(Dispatcher* dispatcher, const void* target_interface);
+  PPB_PDF_Proxy(Dispatcher* dispatcher);
   virtual ~PPB_PDF_Proxy();
 
   static const Info* GetInfo();
 
-  const PPB_PDF* ppb_pdf_target() const {
-    return static_cast<const PPB_PDF*>(target_interface());
-  }
-
   // InterfaceProxy implementation.
   virtual bool OnMessageReceived(const IPC::Message& msg);
 
@@ -39,6 +35,11 @@ class PPB_PDF_Proxy : public InterfaceProxy {
   void OnMsgGetFontTableForPrivateFontFile(const ppapi::HostResource& font_file,
                                            uint32_t table,
                                            std::string* 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_PDF* ppb_pdf_impl_;
 };
 
 }  // namespace proxy