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

native_client_sdk/src/libraries/ppapi_simple/ps_main.cc

 // 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.
 
+#ifdef __native_client__
+#include <irt.h>
+#include <irt_ppapi.h>
+#endif
+
+#include <stdio.h>
+
+#include "nacl_io/nacl_io.h"
 #include "ppapi/c/pp_instance.h"
 #include "ppapi/c/pp_module.h"
-
 #include "ppapi_simple/ps_instance.h"
 #include "ppapi_simple/ps_main.h"
 
+extern "C" int PpapiPluginMain();
 
-void* PSMainCreate(PP_Instance inst, PSMainFunc_t func) {
+void* PSMainCreate(PP_Instance inst) {
   PSInstance* pInst = new PSInstance(inst);
-  pInst->SetMain(func);
+  pInst->SetMain(PSUserMainGet());
   return pInst;
 }
+
+/**
+ * main entry point for ppapi_simple applications.  This differs from the
+ * regular ppapi main entry point in that it will fall back to running
+ * the user's main code in the case that the PPAPI hooks are not found.
+ * This allows ppapi_simple binary to run within chrome (with PPAPI present)
+ * and also under sel_ldr (no PPAPI).
+ */
+int main(int argc, char* argv[]) {
+#ifdef __native_client__
+  struct nacl_irt_ppapihook hooks;
+  if (nacl_interface_query(NACL_IRT_PPAPIHOOK_v0_1, &hooks, sizeof(hooks)) ==
+      sizeof(hooks)) {
+    return PpapiPluginMain();
+  }
+#endif
+  // By default, or if not running in the browser we simply run the main
+  // entry point directly, on the main thread.
+  nacl_io_init();
+  return PSUserMainGet()(argc, argv);
+}