Update the linux ARM root image.

build/linux/install-arm-sysroot.py

Index: build/linux/install-arm-sysroot.py
diff --git a/build/linux/install-arm-sysroot.py b/build/linux/install-arm-sysroot.py
index 56be4a578d88d6364624b7a71b6ccbc974c52be4..523e56e4a2b2768880740ebb6f978cc355d63e18 100755
--- a/build/linux/install-arm-sysroot.py
+++ b/build/linux/install-arm-sysroot.py
@@ -3,16 +3,24 @@
 # 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
@@ -23,7 +31,7 @@ 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'