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

components/nacl/loader/nacl_listener.h

Index: components/nacl/loader/nacl_listener.h
diff --git a/components/nacl/loader/nacl_listener.h b/components/nacl/loader/nacl_listener.h
index 9e8d67b65747d96b35f3391e7bb95a22faf55f0a..eccbc1925b752aa9d80d0eb45b9cbf43e12a2448 100644
--- a/components/nacl/loader/nacl_listener.h
+++ b/components/nacl/loader/nacl_listener.h
@@ -48,6 +48,10 @@ class NaClListener : public IPC::Listener {
 
   void* crash_info_shmem_memory() const { return crash_info_shmem_->memory(); }
 
+  NaClTrustedListener* trusted_listener() const {
+    return trusted_listener_.get();
+  }
+
   typedef base::Callback<void(IPC::PlatformFileForTransit, base::FilePath)>
       ResolveFileTokenCallback;
   void ResolveFileToken(uint64_t token_lo,