Add a script to put in a rootfs from one image into another.

scripts/image_signing/sign_official_build.sh

 #!/bin/bash
 
 # Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # Sign the final build image using the "official" keys.
 #
 # Prerequisite tools needed in the system path:
 #
@@ skipping 168 matching lines @@
   else
     return 1
   fi
 }
 
 # Re-sign the firmware AU payload inside the image rootfs with a new keys.
 # Args: IMAGE
 resign_firmware_payload() {
   local image=$1
 
+  if [ -n "${NO_FWUPDATE}" ]; then
+    echo "Skipping firmware update."
+    return
+  fi
+
   # Grab firmware image from the autoupdate shellball.
   local rootfs_dir=$(make_temp_dir)
   mount_image_partition ${image} 3 ${rootfs_dir}
   # Force unmount of the rootfs on function exit as it is needed later.
   trap "sudo umount -d ${rootfs_dir}" RETURN
 
   local shellball_dir=$(make_temp_dir)
   # get_firmwarebin_from_shellball can fail if the image has no 
   # firmware update.
   get_firmwarebin_from_shellball \
@@ skipping 161 matching lines @@
 elif [ "${TYPE}" == "install" ]; then
   resign_firmware_payload ${INPUT_IMAGE}
   update_rootfs_hash ${INPUT_IMAGE} \
     ${KEY_DIR}/installer_kernel.keyblock \
     ${KEY_DIR}/recovery_kernel_data_key.vbprivk
   sign_for_factory_install
 else
   echo "Invalid type ${TYPE}"
   exit 1
 fi