[Chromoting] Add more logging to Mac install script.

remoting/host/installer/mac/Scripts/remoting_preflight.sh

 #!/bin/sh
 
 # 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.
 
 # Version = @@VERSION@@
 
 HELPERTOOLS=/Library/PrivilegedHelperTools
 SERVICE_NAME=org.chromium.chromoting
@@ skipping 40 matching lines @@
     return 1
   fi
 }
 
 trap on_error ERR
 
 logger Running Chrome Remote Desktop preflight script @@VERSION@@
 
 # If there is an _enabled file, rename it while upgrading.
 if [[ -f "$ENABLED_FILE" ]]; then
+  logger Moving _enabled file
   mv "$ENABLED_FILE" "$ENABLED_FILE_BACKUP"
 fi
 
 # Stop and unload the service for each user currently running the service, and
 # record the user IDs so the service can be restarted for the same users in the
 # postflight script.
 rm -f "$USERS_TMP_FILE"
 
 for uid in $(find_users_with_active_hosts); do
+  logger Unloading service for user "$uid"
   if [[ -n "$uid" ]]; then
     echo "$uid" >> "$USERS_TMP_FILE"
     if [[ "$uid" = "0" ]]; then
       context="LoginWindow"
     else
       context="Aqua"
     fi
 
     sudo_user="sudo -u #$uid"
     stop="launchctl stop $SERVICE_NAME"
     unload="launchctl unload -w -S $context $PLIST"
 
     if is_el_capitan_or_newer; then
       boostrap_user="launchctl asuser $uid"
     else
       # Load the launchd agent in the bootstrap context of user $uid's
       # graphical session, so that screen-capture and input-injection can
       # work. To do this, find the PID of a process which is running in that
       # context. The loginwindow process is a good candidate since the user
       # (if logged in to a session) will definitely be running it.
       pid="$(find_login_window_for_user "$uid")"
       if [[ ! -n "$pid" ]]; then
         exit 1
       fi
       bootstrap_user="launchctl bsexec $pid"
     fi
 
+    logger $bootstrap_user $sudo_user $stop
     $bootstrap_user $sudo_user $stop
+    logger $bootstrap_user $sudo_user $unload
     $bootstrap_user $sudo_user $unload
   fi
 done
 
 exit 0