AU: If firmware updater requests it, fail the update, but request user reboot.

Also, we are changing the return code from 2 to 3, since 2 is a reserved
return code.

TEST=unittests; on device test
BUG=chromium-os:14343

Change-Id: I69af6583e8438c40ea983b320702e76d4c119a38
Reviewed-on: http://gerrit.chromium.org/gerrit/2219
Tested-by: Andrew de los Reyes <adlr@chromium.org>
Reviewed-by: Darin Petkov <petkov@chromium.org>
diff --git a/postinstall_runner_action.cc b/postinstall_runner_action.cc
index 20989aa..7ee4143 100644
--- a/postinstall_runner_action.cc
+++ b/postinstall_runner_action.cc
@@ -67,7 +67,7 @@
   ScopedTempUnmounter temp_unmounter(temp_rootfs_dir_);
   if (return_code != 0) {
     LOG(ERROR) << "Postinst command failed with code: " << return_code;
-    if (return_code == 2) {
+    if (return_code == 3) {
       // This special return code means that we tried to update firmware,
       // but couldn't because we booted from FW B, and we need to reboot
       // to get back to FW A.