Use DBUS_FATAL_WARNINGS=0 environment variable on Chrome just like as Ubuntu.

session_manager_setup.sh

 #!/bin/sh
 
 # 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.
 
 XAUTH=/usr/bin/xauth
 XAUTH_FILE="/var/run/chromelogin.auth"
 SERVER_READY=
 
@@ skipping 10 matching lines @@
 
 export USER=chronos
 export DATA_DIR=/home/${USER}
 export LOGIN_PROFILE_DIR=${DATA_DIR}/Default
 export LOGNAME=${USER}
 export SHELL=/bin/bash
 export HOME=${DATA_DIR}/user
 export DISPLAY=:0.0
 export PATH=/bin:/usr/bin:/usr/local/bin:/usr/bin/X11
 export GTK_IM_MODULE=ibus
+# By default, libdbus treats all warnings as fatal errors. That's too strict.
+export DBUS_FATAL_WARNINGS=0
 
 # Uncomment this to turn on chrome logs.
 # They will be be output to /home/chrome/chrome_log
 # and preserved in /home/chrome/chrome_old_logs
 #ENABLE_CHROME_LOGGING=YES
 
 if [ -n "$ENABLE_CHROME_LOGGING" ] ; then
   CHROME_LOG=${DATA_DIR}/chrome_log
   CHROME_OLD_LOGS=${DATA_DIR}/chrome_old_logs
   # Forces Chrome to put its log into the home directory.
@@ skipping 105 matching lines @@
             --enable-chat-manager \
             --log-level=0 \
             "$CHROME_LOG_FLAG" \
             --main-menu-url="http://welcome-cros.appspot.com/menu" \
             --no-first-run \
             --user-data-dir=/home/$USER \
             --login-profile=user \
             --in-chrome-auth \
             --enable-login-images \
             "${SKIP_OOBE}"