Use helper function.

config/chroot_local-includes/usr/local/lib/tails-shell-library/chroot-browser.sh

@@ -7,27 +7,18 @@
 # Import windows_camouflage_is_enabled()
 . /usr/local/lib/tails-shell-library/tails-greeter.sh
 
+# Import try_for().
+. /usr/local/lib/tails-shell-library/common.sh
+
 # Break down the chroot and kill all of its processes
 try_cleanup_browser_chroot () {
     local chroot="${1}"
     local cow="${2}"
     local user="${3}"
-    local counter=0
-    local ret=0
-    while [ "${counter}" -le 10 ] && pgrep -u ${user} 1>/dev/null 2>&1; do
-        pkill -u ${user} 1>/dev/null 2>&1
-        ret=${?}
-        sleep 1
-        counter=$((${counter}+1))
-    done
-    [ ${ret} -eq 0 ] || pkill -9 -u ${user} 1>/dev/null 2>&1
+    try_for 10 "pkill -u ${user} 1>/dev/null 2>&1" || \
+        pkill -9 -u ${user} 1>/dev/null 2>&1
     for mnt in ${chroot}/dev ${chroot}/proc ${chroot} ${cow}; do
-        counter=0
-        while [ "${counter}" -le 10 ] && mountpoint -q ${mnt} 2>/dev/null; do
-            umount ${mnt} 2>/dev/null
-            sleep 1
-            counter=$((${counter}+1))
-        done
+        try_for 10 "umount ${mnt} 2>/dev/null"
     done
     rmdir ${cow} ${chroot} 2>/dev/null
 }

config/chroot_local-includes/usr/local/lib/tails-shell-library/common.sh

@@ -14,3 +14,9 @@ wait_until() {
     done
     return 0
 }
+
+# Just an alias. The second argument (wait_until()'s check_expr) is
+# the "try code block".
+try_for() {
+    wait_until "${@}"
+}