PPAPI: Make blocking completion callbacks work.

ppapi/thunk/ppb_talk_private_api.h

Index: ppapi/thunk/ppb_talk_private_api.h
diff --git a/ppapi/thunk/ppb_talk_private_api.h b/ppapi/thunk/ppb_talk_private_api.h
index 8f5244d133ae38837053cb4c2e7ffed2d403ad24..5a4f06c1b9c975a6ed7ec3216bfbe4b457ca1396 100644
--- a/ppapi/thunk/ppb_talk_private_api.h
+++ b/ppapi/thunk/ppb_talk_private_api.h
@@ -5,16 +5,20 @@
 #ifndef PPAPI_THUNK_PPB_TALK_PRIVATE_API_H_
 #define PPAPI_THUNK_PPB_TALK_PRIVATE_API_H_
 
+#include "base/memory/ref_counted.h"
 #include "ppapi/thunk/ppapi_thunk_export.h"
 
 namespace ppapi {
+
+class TrackedCallback;
+
 namespace thunk {
 
 class PPAPI_THUNK_EXPORT PPB_Talk_Private_API {
  public:
   virtual ~PPB_Talk_Private_API() {}
 
-  virtual int32_t GetPermission(const PP_CompletionCallback& callback) = 0;
+  virtual int32_t GetPermission(scoped_refptr<TrackedCallback> callback) = 0;
 };
 
 }  // namespace thunk