Changes to enable dev in stateful partition for usb and startup

src/platform/init/chromeos_startup

 #!/bin/sh
 
 # Copyright (c) 2009 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.
 
 HAS_INITRAMFS=0
 if [ -d /dev/.initramfs ]
 then
   # The initrd will have mounted /sys, /proc, and /dev for us.
@@ skipping 53 matching lines @@
 # Default to Pacific timezone if we don't have one set
 ! ln -s /usr/share/zoneinfo/US/Pacific /mnt/stateful_partition/etc/localtime \
     > /dev/null 2>&1
 
 # Mount some /var directories and /home
 mount -n --bind /mnt/stateful_partition/var/cache /var/cache
 mount -n --bind /mnt/stateful_partition/var/log /var/log
 mount -n -t tmpfs -omode=1777,nodev,noexec,nosuid vartmp /var/tmp
 mount -n --bind /mnt/stateful_partition/home /home
 
+# Mount stateful partition for dev packages
+# TODO(sosa@chromium.org) - Use kernel flag
+if [ -f /root/.dev_mode ] ; then
+  mount -n --bind /mnt/stateful_partition/dev_image /usr/local
+fi
+
 mount -n -t tmpfs -omode=0755,nosuid varrun /var/run
 touch /var/run/.ramfs  # TODO: Is this needed?
 mount -n -t tmpfs -omode=1777,nodev,noexec,nosuid varlock /var/lock
 touch /var/lock/.ramfs # TODO: Is this needed?
 mount -n -t tmpfs media /media
 
 # Some things freak out if no hostname is set.
 hostname localhost
 
 # create salt for user data dir crypto
 mkdir -p /home/.shadow
 SALT=/home/.shadow/salt
 (test -f "$SALT" || head -c 16 /dev/urandom > "$SALT") &
 
 # Write out uptime and disk stats pre/post startup
 cat /proc/uptime > /tmp/uptime-post-startup
 ! cat /sys/block/sda/stat > /tmp/disk-post-startup
 echo "$PRE_UPTIME_STAT" > /tmp/uptime-pre-startup
 echo "$PRE_DISK_STAT" > /tmp/disk-pre-startup
 
 # Always return success to avoid killing init
 exit 0