Listen Developer option enable state

- When developer option disabled, any page in Developer option
  should be closed.

Bug: 293894425
Test: manual

Change-Id: I392b122e885118770be1af2b51c0c7ef92279e1b

src/com/android/settings/development/featureflags/FeatureFlagsDashboard.java

@@ -22,8 +22,8 @@ import android.provider.SearchIndexableResource;
 
 import com.android.settings.R;
 import com.android.settings.dashboard.DashboardFragment;
+import com.android.settings.development.DeveloperOptionAwareMixin;
 import com.android.settings.search.BaseSearchIndexProvider;
-import com.android.settingslib.search.Indexable;
 import com.android.settingslib.development.DevelopmentSettingsEnabler;
 import com.android.settingslib.search.SearchIndexable;
 
@@ -31,7 +31,8 @@ import java.util.ArrayList;
 import java.util.List;
 
 @SearchIndexable
-public class FeatureFlagsDashboard extends DashboardFragment {
+public class FeatureFlagsDashboard extends DashboardFragment implements
+        DeveloperOptionAwareMixin {
 
     private static final String TAG = "FeatureFlagsDashboard";
 
@@ -50,11 +51,6 @@ public class FeatureFlagsDashboard extends DashboardFragment {
         return R.xml.feature_flags_settings;
     }
 
-    @Override
-    public void onAttach(Context context) {
-        super.onAttach(context);
-    }
-
     @Override
     public int getHelpResource() {
         return 0;