PPAPI: Make blocking completion callbacks work.

ppapi/thunk/ppb_audio_input_thunk.cc

Index: ppapi/thunk/ppb_audio_input_thunk.cc
diff --git a/ppapi/thunk/ppb_audio_input_thunk.cc b/ppapi/thunk/ppb_audio_input_thunk.cc
index 9102dc588b9d5c4516d661dd3bad5097c7f92b8e..2cd811ba02a75ed824a87b7fb0c42716259adb25 100644
--- a/ppapi/thunk/ppb_audio_input_thunk.cc
+++ b/ppapi/thunk/ppb_audio_input_thunk.cc
@@ -49,7 +49,8 @@ int32_t EnumerateDevices(PP_Resource audio_input,
   if (enter.failed())
     return enter.retval();
 
-  return enter.SetResult(enter.object()->EnumerateDevices(devices, callback));
+  return enter.SetResult(enter.object()->EnumerateDevices(devices,
+                                                          enter.callback()));
 }
 
 int32_t Open(PP_Resource audio_input,
@@ -73,7 +74,7 @@ int32_t Open(PP_Resource audio_input,
   }
 
   return enter.SetResult(enter.object()->Open(
-      device_id, config, audio_input_callback, user_data, callback));
+      device_id, config, audio_input_callback, user_data, enter.callback()));
 }
 
 PP_Resource GetCurrentConfig(PP_Resource audio_input) {