Make a global enum to differentiate impl & proxy.

chrome/renderer/chrome_ppb_pdf_impl.cc

Index: chrome/renderer/chrome_ppb_pdf_impl.cc
diff --git a/chrome/renderer/chrome_ppb_pdf_impl.cc b/chrome/renderer/chrome_ppb_pdf_impl.cc
index c5d0261dcfd24cebaeca47a89065a02305ae8dae..a824366002c3880333301c09e388bba896d80ba6 100644
--- a/chrome/renderer/chrome_ppb_pdf_impl.cc
+++ b/chrome/renderer/chrome_ppb_pdf_impl.cc
@@ -48,7 +48,9 @@ namespace chrome {
 #if defined(OS_LINUX) || defined(OS_OPENBSD)
 class PrivateFontFile : public ppapi::Resource {
  public:
-  PrivateFontFile(PP_Instance instance, int fd) : Resource(instance), fd_(fd) {
+  PrivateFontFile(PP_Instance instance, int fd)
+      : Resource(ppapi::OBJECT_IS_IMPL, instance),
+        fd_(fd) {
   }
   virtual ~PrivateFontFile() {
   }