Update the linux ARM root image.

build/linux/install-arm-sysroot.py

 #!/usr/bin/env python
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-# Script to install ARM root image for cross building of ARM chrome on linux.
-# This script can be run manually but is more often run as part of gclient
-# hooks. When run from hooks this script should be a no-op on non-linux
-# platforms.
+"""Script to install ARM root image for cross building of ARM chrome on linux.
+This script can be run manually but is more often run as part of gclient
+hooks. When run from hooks this script should be a no-op on non-linux
+platforms.
 
-# The sysroot image could be constructed from scratch based on the current
-# state or precise/arm but for consistency we currently use a pre-built root
-# image which was originally designed for building trusted NaCl code. The image
-# will normally need to be rebuilt every time chrome's build dependancies are
-# changed.
+The sysroot image could be constructed from scratch based on the current
+state or precise/arm but for consistency we currently use a pre-built root
+image which was originally designed for building trusted NaCl code. The image
+will normally need to be rebuilt every time chrome's build dependancies are
+changed.
+
+Steps to rebuild the arm sysroot image:
+
+- cd $SRC/native_client
+- ./tools/trusted_cross_toolchains/trusted-toolchain-creator.armel.precise.sh  UpdatePackageLists
+- ./tools/trusted_cross_toolchains/trusted-toolchain-creator.armel.precise.sh  BuildJail $SRC/out/arm-sysroot.tar.gz
+- gsutil cp -a public-read $SRC/out/arm-sysroot.tar.gz nativeclient-archive2/toolchain/$NACL_REV/naclsdk_linux_arm-trusted.tgz
+"""
 
 import os
 import shutil
 import subprocess
 import sys
 
 
 SCRIPT_DIR = os.path.dirname(os.path.abspath(__file__))
 URL_PREFIX = 'https://commondatastorage.googleapis.com'
 URL_PATH = 'nativeclient-archive2/toolchain'
-REVISION = 10991
+REVISION = 12203
 TARBALL = 'naclsdk_linux_arm-trusted.tgz'
 
 
 def main(args):
   if '--linux-only' in args:
     # This argument is passed when run from the gclient hooks.
     # In this case we return early on non-linux platforms
     # or if GYP_DEFINES doesn't include target_arch=arm
     if not sys.platform.startswith('linux'):
       return 0
@@ skipping 21 matching lines @@
   subprocess.check_call(['tar', 'xf', tarball, '-C', sysroot])
   os.remove(tarball)
 
   with open(stamp, 'w') as s:
     s.write(url)
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))