Fixing crash in SettingsCache

Bug: 301119252
Test: Presubmit
Flag: N/A
Change-Id: I1356e6c6ad693cc53716603a0a2ca5efd6af5ea9

src/com/android/launcher3/util/SettingsCache.java

@@ -154,7 +154,7 @@ public class SettingsCache extends ContentObserver implements SafeCloseable {
      */
     public void unregister(Uri uri, OnChangeListener listener) {
         List<OnChangeListener> listenersToRemoveFrom = mListenerMap.get(uri);
-        if (!listenersToRemoveFrom.contains(listener)) {
+        if (listenersToRemoveFrom == null) {
             return;
         }