Make PreferenceController a mixin

Bug: 62912136
Test: Existing tests in BaseSearchIndexProviderTest
Change-Id: Ieda359806c09a019840b2005446c7ec8b61fdb00
diff --git a/src/com/android/settings/DisplaySettings.java b/src/com/android/settings/DisplaySettings.java
index 9ce4c4a..a7d18df 100644
--- a/src/com/android/settings/DisplaySettings.java
+++ b/src/com/android/settings/DisplaySettings.java
@@ -21,7 +21,6 @@
 
 import com.android.internal.hardware.AmbientDisplayConfiguration;
 import com.android.internal.logging.nano.MetricsProto.MetricsEvent;
-import com.android.settings.core.PreferenceController;
 import com.android.settings.dashboard.DashboardFragment;
 import com.android.settings.display.AmbientDisplayPreferenceController;
 import com.android.settings.display.AutoBrightnessPreferenceController;
@@ -41,6 +40,7 @@
 import com.android.settings.display.WallpaperPreferenceController;
 import com.android.settings.search.BaseSearchIndexProvider;
 import com.android.settings.search.Indexable;
+import com.android.settingslib.core.AbstractPreferenceController;
 import com.android.settingslib.core.lifecycle.Lifecycle;
 
 import java.util.ArrayList;
@@ -77,7 +77,7 @@
     }
 
     @Override
-    protected List<PreferenceController> getPreferenceControllers(Context context) {
+    protected List<AbstractPreferenceController> getPreferenceControllers(Context context) {
         return buildPreferenceControllers(context, getLifecycle());
     }
 
@@ -86,9 +86,9 @@
         return R.string.help_uri_display;
     }
 
-    private static List<PreferenceController> buildPreferenceControllers(
+    private static List<AbstractPreferenceController> buildPreferenceControllers(
             Context context, Lifecycle lifecycle) {
-        final List<PreferenceController> controllers = new ArrayList<>();
+        final List<AbstractPreferenceController> controllers = new ArrayList<>();
         final AmbientDisplayConfiguration ambientDisplayConfig = new AmbientDisplayConfiguration(context);
         controllers.add(new AutoBrightnessPreferenceController(context, KEY_AUTO_BRIGHTNESS));
         controllers.add(new AutoRotatePreferenceController(context, lifecycle));
@@ -131,7 +131,7 @@
                 }
 
                 @Override
-                public List<PreferenceController> getPreferenceControllers(Context context) {
+                public List<AbstractPreferenceController> getPreferenceControllers(Context context) {
                     return buildPreferenceControllers(context, null);
                 }
             };