Handle updates to the wrapper script.

remoting/host/installer/linux/debian/postinst

Index: remoting/host/installer/linux/debian/postinst
diff --git a/remoting/host/installer/linux/debian/postinst b/remoting/host/installer/linux/debian/postinst
index 68b8d5892978cc68d905af716edaa5a3ea0f2577..c7c7e8ae6c99d37c538cf37a1de374815224d66c 100755
--- a/remoting/host/installer/linux/debian/postinst
+++ b/remoting/host/installer/linux/debian/postinst
@@ -1,11 +1,42 @@
 #!/bin/bash
 
+# 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.
+
 set -e
 
-case $1 in
+LOGOUT_MSG="
+Name: Please log out to update
+Priority: Medium
+OnlyAdminUsers: False
+DontShowAfterReboot: true
+DisplayIf: /usr/lib/chrome-remote-desktop/is_me2me_desktop
+Description: Chrome Remote Desktop has been updated. Please save your work and log out in order to apply this update. Your virtual desktop will be restarted automatically.
+"
+
+NOTIFIER_DIR="/var/lib/update-notifier/user.d"
+VAR_DIR="/var/lib/chrome-remote-desktop"
+HASHES_FILE="$VAR_DIR/hashes"
+
+case "$1" in
   "configure")
+    # Kill me2me host processes. The wrapper script will restart them.
     echo "Shutting down remoting hosts (they will restart automatically)..."
     killall -q remoting_me2me_host || true
+    # If any files have changed that require the user to restart their virtual
+    # desktops (eg, the wrapper script itself) then notify them but don't do
+    # anything that would result in them losing state.
+    if [ -f "$HASHES_FILE" ]; then
+      if [ -d "$NOTIFIER_DIR" ]; then
+        if ! md5sum --status -c "$HASHES_FILE"; then
+          echo "Sending logout notification messages to virtual desktops."
+          echo "$LOGOUT_MSG" > "$NOTIFIER_DIR/chrome-remote-desktop-logout"
+        fi
+      fi
+      rm "$HASHES_FILE"
+      rmdir --ignore-fail-on-non-empty "$VAR_DIR"
+    fi
     ;;
 esac