PPAPI: Make blocking completion callbacks work.

ppapi/proxy/ppb_audio_proxy.cc

Index: ppapi/proxy/ppb_audio_proxy.cc
diff --git a/ppapi/proxy/ppb_audio_proxy.cc b/ppapi/proxy/ppb_audio_proxy.cc
index fe890ae381ce994d7928beebcc718652fcabfa78..24ce9a684c9c6a82294d6d3cbf7dbe30ce21a5c6 100644
--- a/ppapi/proxy/ppb_audio_proxy.cc
+++ b/ppapi/proxy/ppb_audio_proxy.cc
@@ -48,7 +48,7 @@ class Audio : public Resource, public PPB_Audio_Shared {
   virtual PP_Bool StartPlayback() OVERRIDE;
   virtual PP_Bool StopPlayback() OVERRIDE;
   virtual int32_t OpenTrusted(PP_Resource config_id,
-                              PP_CompletionCallback create_callback) OVERRIDE;
+                              ApiCallbackType create_callback) OVERRIDE;
   virtual int32_t GetSyncSocket(int* sync_socket) OVERRIDE;
   virtual int32_t GetSharedMemory(int* shm_handle, uint32_t* shm_size) OVERRIDE;
 
@@ -105,7 +105,7 @@ PP_Bool Audio::StopPlayback() {
 }
 
 int32_t Audio::OpenTrusted(PP_Resource config_id,
-                           PP_CompletionCallback create_callback) {
+                           ApiCallbackType create_callback) {
   return PP_ERROR_NOTSUPPORTED;  // Don't proxy the trusted interface.
 }