Fix NPE when using VisibilityLogger.

Fix: 31612160
Test: make RunSettingsRoboTests
Change-Id: Ib040a40d27a76d9440f629ed4f768dc4bfde8ac2

src/com/android/settings/ZonePicker.java

@@ -136,6 +136,12 @@ public class ZonePicker extends ListFragment implements Instrumentable {
         return TimeZone.getTimeZone((String)((Map<?, ?>)item).get(ZoneGetter.KEY_ID));
     }
 
+    @Override
+    public void onAttach(Context context) {
+        super.onAttach(context);
+        mVisibilityLoggerMixin.onAttach(context);
+    }
+
     @Override
     public int getMetricsCategory() {
         return MetricsProto.MetricsEvent.ZONE_PICKER;