Be less verbose while changing the password. Add a script for checking if password already exists.

scripts/image_signing/set_chronos_password.sh

Index: scripts/image_signing/set_chronos_password.sh
diff --git a/scripts/image_signing/set_chronos_password.sh b/scripts/image_signing/set_chronos_password.sh
index 1319dbf5ba9eb55b10417fdb7b6ea8612707724e..e3a335536cf240298818acdd34da93d346970903 100755
--- a/scripts/image_signing/set_chronos_password.sh
+++ b/scripts/image_signing/set_chronos_password.sh
@@ -14,7 +14,7 @@
 change_chronos_password() {
   local rootfs=$1
   local password=$2
-  echo "Changing chronos password to '$password'..."
+  echo "Setting chronos password..."
   local crypted_password="$(echo $password | openssl passwd -1 -stdin)"
   local temp_shadow="$rootfs/etc/tempshadow"
   echo "chronos:$crypted_password:14500:0:99999::::" \
@@ -47,7 +47,7 @@ main() {
   mount_image_partition "$image" 3 "$rootfs"
   change_chronos_password "$rootfs" "$chronos_password"
   touch "$image"  # Updates the image modification time.
-  echo "Password Changed."
+  echo "Password Set."
 }
 
 main $@