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

components/nacl/common/nacl_renderer_messages.h

Index: components/nacl/common/nacl_renderer_messages.h
diff --git a/components/nacl/common/nacl_renderer_messages.h b/components/nacl/common/nacl_renderer_messages.h
index e07a08267ddb900e1f0c878631c7e2599a5d0196..265af86fa006ea8955ff138cfb2b0a9b4e145dba 100644
--- a/components/nacl/common/nacl_renderer_messages.h
+++ b/components/nacl/common/nacl_renderer_messages.h
@@ -6,6 +6,7 @@
 
 // Multiply-included message file, no traditional include guard.
 #include "ipc/ipc_message_macros.h"
+#include "native_client/src/trusted/service_runtime/nacl_error_code.h"
 
 #define IPC_MESSAGE_START NaClHostMsgStart
 
@@ -13,3 +14,10 @@
 // NaCl to the renderer before the NaCl process exits very soon after.
 IPC_SYNC_MESSAGE_CONTROL1_0(NaClRendererMsg_ReportExitStatus,
                             int /* exit_status */)
+
+IPC_ENUM_TRAITS_MAX_VALUE(NaClErrorCode, NACL_ERROR_CODE_MAX)
+
+// This message must be synchronous to ensure that the load status is sent from
+// NaCl to the renderer before the NaCl process exits very soon after.
+IPC_SYNC_MESSAGE_CONTROL1_0(NaClRendererMsg_ReportLoadStatus,
+                            NaClErrorCode /* load_status */)