Instantiate pref controllers from xml if it's defined.

- If a <preference> tag also defines a controller, we will try to
  instantiate it before displaying the UI. The same logic is shared by
  BaseSearchIndexProvider so it also drives search suppression.

- If user also defines a list of controllers programatically, the
  programatically created ones takes precedence.

Bug: 73668763
Test: WIP
Change-Id: I7aecec270bcd3af261e012ef1f6995d2a523cfa1

src/com/android/settings/system/SystemDashboardFragment.java

@@ -26,12 +26,9 @@ import com.android.internal.logging.nano.MetricsProto;
 import com.android.settings.R;
 import com.android.settings.backup.BackupSettingsActivityPreferenceController;
 import com.android.settings.dashboard.DashboardFragment;
-import com.android.settings.gestures.GesturesSettingPreferenceController;
 import com.android.settings.search.BaseSearchIndexProvider;
 import com.android.settings.search.Indexable;
-import com.android.settingslib.core.AbstractPreferenceController;
 
-import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 
@@ -72,20 +69,6 @@ public class SystemDashboardFragment extends DashboardFragment {
         return R.string.help_url_system_dashboard;
     }
 
-    @Override
-    protected List<AbstractPreferenceController> getPreferenceControllers(Context context) {
-        return buildPreferenceControllers(context);
-    }
-
-    private static List<AbstractPreferenceController> buildPreferenceControllers(Context context) {
-        final List<AbstractPreferenceController> controllers = new ArrayList<>();
-        controllers.add(new SystemUpdatePreferenceController(context));
-        controllers.add(new AdditionalSystemUpdatePreferenceController(context));
-        controllers.add(new BackupSettingsActivityPreferenceController(context));
-        controllers.add(new GesturesSettingPreferenceController(context));
-        return controllers;
-    }
-
     private int getVisiblePreferenceCount(PreferenceGroup group) {
         int visibleCount = 0;
         for (int i = 0; i < group.getPreferenceCount(); i++) {
@@ -112,12 +95,6 @@ public class SystemDashboardFragment extends DashboardFragment {
                     return Arrays.asList(sir);
                 }
 
-                @Override
-                public List<AbstractPreferenceController> getPreferenceControllers(
-                        Context context) {
-                    return buildPreferenceControllers(context);
-                }
-
                 @Override
                 public List<String> getNonIndexableKeys(Context context) {
                     List<String> keys = super.getNonIndexableKeys(context);