Add support for threadsafe completion callback factory.

ppapi/proxy/ppb_audio_proxy.h

Index: ppapi/proxy/ppb_audio_proxy.h
diff --git a/ppapi/proxy/ppb_audio_proxy.h b/ppapi/proxy/ppb_audio_proxy.h
index d8fe9a0263d465c421b24c55119ca0ba966c67b4..b5169258cc627f7d384eeaa280767f7fb331ee40 100644
--- a/ppapi/proxy/ppb_audio_proxy.h
+++ b/ppapi/proxy/ppb_audio_proxy.h
@@ -16,7 +16,7 @@
 #include "ppapi/c/ppb_audio.h"
 #include "ppapi/c/ppb_audio_config.h"
 #include "ppapi/proxy/interface_proxy.h"
-#include "ppapi/proxy/proxy_non_thread_safe_ref_count.h"
+#include "ppapi/proxy/proxy_completion_callback_factory.h"
 #include "ppapi/utility/completion_callback_factory.h"
 
 namespace ppapi {
@@ -74,8 +74,7 @@ class PPB_Audio_Proxy : public InterfaceProxy {
       base::SharedMemoryHandle* foreign_shared_memory_handle,
       uint32_t* shared_memory_length);
 
-  pp::CompletionCallbackFactory<PPB_Audio_Proxy,
-                                ProxyNonThreadSafeRefCount> callback_factory_;
+  ProxyCompletionCallbackFactory<PPB_Audio_Proxy> callback_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PPB_Audio_Proxy);
 };