[NaCl SDK] Allow ppapi_simple executables to run in both sel_ldr and in chrome.

native_client_sdk/src/libraries/ppapi_simple/ps_main.h

 /* Copyright (c) 2012 The Chromium Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file. */
 
 #ifndef PPAPI_SIMPLE_PS_MAIN_H_
 #define PPAPI_SIMPLE_PS_MAIN_H_
 
 #include "ppapi_simple/ps.h"
 #include "ppapi_simple/ps_event.h"
 
 EXTERN_C_BEGIN
 
 typedef int (*PSMainFunc_t)(int argc, char *argv[]);
 
 /**
  * PSMainCreate
  *
  * Constructs an instance SimpleInstance and configures it to call into
  * the provided "main" function.
  */
-void* PSMainCreate(PP_Instance inst, PSMainFunc_t func);
+void* PSMainCreate(PP_Instance inst);
 
+/**
+ * PSUserMainGet
+ *
+ * Prototype for the user provided function which retrieves the user's main
+ * function.
+ * This is normally defined using the PPAPI_SIMPLE_REGISTER_MAIN macro.
+ */
+PSMainFunc_t PSUserMainGet();
 
 /**
  * PPAPI_SIMPLE_REGISTER_MAIN
  *
  * Constructs a PSInstance object and configures it to use call the provided
  * 'main' function on its own thread once initialization is complete.
  */
-#define PPAPI_SIMPLE_REGISTER_MAIN(main) \
-  PPAPI_SIMPLE_USE_MAIN(PSMainCreate, main)
+#define PPAPI_SIMPLE_REGISTER_MAIN(main_func)    \
+  void* PSUserCreateInstance(PP_Instance inst) { \
+    return PSMainCreate(inst);                   \
+  }                                              \
+  PSMainFunc_t PSUserMainGet() {                 \
+    return main_func;                            \
+  }
 
 EXTERN_C_END
 
 #endif  /* PPAPI_SIMPLE_PS_MAIN_H_ */