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

native_client_sdk/src/libraries/ppapi_simple/ps.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.
 
 #include "ppapi/c/pp_instance.h"
 #include "ppapi/c/pp_module.h"
 
 #include "ppapi/cpp/instance.h"
 #include "ppapi/cpp/module.h"
 
 #include "ppapi_simple/ps.h"
 
 static pp::Instance* s_Instance = NULL;
 
-PP_Instance PSGetInstanceId() {
+PP_Instance PSGetInstanceId(void) {
+  if (s_Instance == NULL)
+    return 0;
   return s_Instance->pp_instance();
 }
 
 const void* PSGetInterface(const char *name) {
-  return pp::Module::Get()->GetBrowserInterface(name);
+  pp::Module* module = pp::Module::Get();
+  if (module == NULL)
+    return NULL;
+  return module->GetBrowserInterface(name);
 }
 
 
 // The Module class.  The browser calls the CreateInstance() method to create
 // an instance of your NaCl module on the web page.  The browser creates a new
 // instance for each <embed> tag with type="application/x-nacl".
 class PSModule : public pp::Module {
  public:
   PSModule() : pp::Module() {}
   virtual ~PSModule() {}
@@ skipping 10 matching lines @@
 // The browser keeps a singleton of this module.  It calls the
 // CreateInstance() method on the object you return to make instances.  There
 // is one instance per <embed> tag on the page.  This is the main binding
 // point for your NaCl module with the browser.
 Module* CreateModule() {
   return new PSModule();
 }
 
 }  // namespace pp