Set up a NaCl load status callback to start replacing "start_module".

components/nacl/renderer/ppb_nacl_private_impl.cc

Index: components/nacl/renderer/ppb_nacl_private_impl.cc
diff --git a/components/nacl/renderer/ppb_nacl_private_impl.cc b/components/nacl/renderer/ppb_nacl_private_impl.cc
index c879e48671bf9e1cb00fc42c3325ba6d162bf16f..53e93d392146129e0a9d09f306ccdafe2c75ba50 100644
--- a/components/nacl/renderer/ppb_nacl_private_impl.cc
+++ b/components/nacl/renderer/ppb_nacl_private_impl.cc
@@ -501,13 +501,12 @@ void LaunchSelLdr(PP_Instance instance,
 
   // Create the trusted plugin channel.
   if (IsValidChannelHandle(launch_result.trusted_ipc_channel_handle)) {
-    bool report_exit_status = PP_ToBool(main_service_runtime);

[Mark Seaborn, 2015/04/18 14:07:53]

Nit: How about:

bool is_helper_nexe = !PP_ToBool(main_service_runtime);
// Then pass is_helper_nexe as the argument.

This just names the argument to make it clearer what its meaning is without
having to look at TrustedPluginChannel's constructor.

     scoped_ptr<TrustedPluginChannel> trusted_plugin_channel(
         new TrustedPluginChannel(
             load_manager,
             launch_result.trusted_ipc_channel_handle,
             content::RenderThread::Get()->GetShutdownEvent(),
-            report_exit_status));
+            !PP_ToBool(main_service_runtime)));

[jvoung (off chromium), 2015/04/18 01:00:47]

I think we can replace this with checking the "PP_NaClAppProcessType
pp_process_type" instead, but I haven't done that.

     load_manager->set_trusted_plugin_channel(trusted_plugin_channel.Pass());
   } else {
     PostPPCompletionCallback(callback, PP_ERROR_FAILED);