Don't removePluginListener() unless user is unlocked

This just crashes since we can't access SharedPreferences, and we don't
addPluginListener until onUserUnlocked() anyway.

Bug: 145019350
Change-Id: I705498f859857a52a2cb5735201a652973b26d0b
(cherry picked from commit 435b11b95fd83901e7c2dc36269442b3c1312c95)
1 file changed