Fix the crash for the AudioShared.

ppapi/proxy/plugin_main_irt.cc

Index: ppapi/proxy/plugin_main_irt.cc
diff --git a/ppapi/proxy/plugin_main_irt.cc b/ppapi/proxy/plugin_main_irt.cc
index 6d576bea0f158da735920cfe06f2950423b7f537..556cd8e284f59a6c3317cebce5e98f3334e57db9 100644
--- a/ppapi/proxy/plugin_main_irt.cc
+++ b/ppapi/proxy/plugin_main_irt.cc
@@ -316,15 +316,9 @@ void SetIPCFileDescriptors(int ipc_browser_fd, int ipc_renderer_fd) {
 
 void PpapiPluginRegisterThreadCreator(
     const struct PP_ThreadFunctions* thread_functions) {
-#if defined(__native_client__)
-  // TODO(hidehiko): The thread creation for the PPB_Audio is not yet
-  // implemented on non-SFI mode. Support this. Now, this function invocation
-  // is just ignored.
-
   // Initialize all classes that need to create threads that call back into
   // user code.
   ppapi::PPB_Audio_Shared::SetThreadFunctions(thread_functions);
-#endif
 }
 
 int PpapiPluginMain() {