Use new grub2 variables to boot from the device with the bootloader

src/platform/installer/chromeos-install

 #!/bin/sh -u
 # 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.
 #
 # A script to install from removable media to hard disk.
 
 # Load functions and constants for chromeos-install.
 . "$(dirname "$0")/chromeos-common.sh" || exit 1
 . /usr/lib/shflags || exit 1
@@ skipping 13 matching lines @@
   "Allow root to run this script (Careful, it won't prompt for a password!)"
 DEFINE_boolean yes ${FLAGS_FALSE} \
   "Answer yes to everything"
 
 # Parse command line
 FLAGS "$@" || exit 1
 eval set -- "${FLAGS_ARGV}"
 
 set -e
 
-# Unless you pass --run_as_root, you can't be root when you start this,
-# because we want to force you to give the root password as confirmation
-# that you're allowed to do it. We don't care what other account you're using;
-# you'll still need to sudo before this works.
-if [ $(id -u) -eq "0" -a "${FLAGS_run_as_root}" -eq "${FLAGS_FALSE}" ]
-then
-  echo "Note: You must be the 'chronos' user to run this script. Unless"
-  echo "you pass --run_as_root and run as root."
-  exit 1
-fi
+# Don't run this as root
+dont_run_as_root
 
 # First find the root partition that we are installing from and verify it.
 ROOTDEV=$(rootdev)
 # From root partition to root block device.
 SRC=$(get_block_dev_from_partition_dev ${ROOTDEV})
 REMOVABLE=$(cat /sys/block/${SRC#/dev/}/removable)
 if [ "$FLAGS_skip_src_removable" -eq "${FLAGS_FALSE}" -a "$REMOVABLE" != "1" ]
 then
   echo "Error: Source does not look like a removable device: $SRC"
   exit 1
@@ skipping 261 matching lines @@
     --set bootcmd="mmc read 0 C0008000 0 1; autoscr C0008000"
 fi
 
 # Force data to disk before we declare done.
 sync
 
 echo "------------------------------------------------------------"
 echo ""
 echo "Installation to '$FLAGS_dst' complete."
 echo "Please shutdown, remove the USB device, cross your fingers, and reboot."