fix launcher crash when accessing Notification dots in home settings

Bug: 148815606
Test:
1.  Make sure launcher doesn't have notifications permission
    (Settings -> search for "notification access" -> Disable access for Launcher)
2.  Home settings -> Notification Dot
3.  Verify Alert Dialog pops up without crash

Change-Id: I399b6aad46e8a3e185199a2909adac9f75596b50
diff --git a/src/com/android/launcher3/settings/NotificationDotsPreference.java b/src/com/android/launcher3/settings/NotificationDotsPreference.java
index f30470a..a91303a 100644
--- a/src/com/android/launcher3/settings/NotificationDotsPreference.java
+++ b/src/com/android/launcher3/settings/NotificationDotsPreference.java
@@ -20,7 +20,6 @@
 
 import android.app.AlertDialog;
 import android.app.Dialog;
-import android.app.DialogFragment;
 import android.content.ComponentName;
 import android.content.Context;
 import android.content.DialogInterface;
@@ -30,13 +29,14 @@
 import android.util.AttributeSet;
 import android.view.View;
 
+import androidx.fragment.app.DialogFragment;
+import androidx.preference.Preference;
+import androidx.preference.PreferenceViewHolder;
+
 import com.android.launcher3.R;
 import com.android.launcher3.notification.NotificationListener;
 import com.android.launcher3.util.SecureSettingsObserver;
 
-import androidx.preference.Preference;
-import androidx.preference.PreferenceViewHolder;
-
 /**
  * A {@link Preference} for indicating notification dots status.
  * Also has utility methods for updating UI based on dots status changes.