Add C++ wrappers for output parameters.

ppapi/examples/audio_input/audio_input.cc

Index: ppapi/examples/audio_input/audio_input.cc
diff --git a/ppapi/examples/audio_input/audio_input.cc b/ppapi/examples/audio_input/audio_input.cc
index 44fd33740098c5b83d007b062253dd4b53ea3da1..7aff669e4db31e2f6e21a9523d59059db1deb428 100644
--- a/ppapi/examples/audio_input/audio_input.cc
+++ b/ppapi/examples/audio_input/audio_input.cc
@@ -130,7 +130,7 @@ class MyInstance : public pp::Instance {
     PP_DCHECK(timer_interval_ > 0);
     pp::Module::Get()->core()->CallOnMainThread(
         timer_interval_,
-        callback_factory_.NewRequiredCallback(&MyInstance::OnTimer),
+        callback_factory_.NewCallback(&MyInstance::OnTimer),
         0);
   }
 
@@ -161,7 +161,7 @@ class MyInstance : public pp::Instance {
       device_context_.ReplaceContents(&image);
       waiting_for_flush_completion_ = true;
       device_context_.Flush(
-          callback_factory_.NewRequiredCallback(&MyInstance::DidFlush));
+          callback_factory_.NewCallback(&MyInstance::DidFlush));
     }
   }