Add display settings dashboard to new IA.

- Added a activity-alias pointing to displaySettings as top level
  setting item.
- Refactored all preference logic in DisplaySettings into
  PreferenceControllers. During fragment onAttach it installs all
  controllers, and during onResume it updates preference state. Each
  controller listens to its own preference change event.

Bug: 31800242
Test: RunSettingsRoboTests
Change-Id: Ibc9bf200c5acce7c4ae9292340822afee27a3a28

src/com/android/settings/deviceinfo/SystemUpdatePreferenceController.java

@@ -25,7 +25,6 @@ import android.telephony.CarrierConfigManager;
 import android.text.TextUtils;
 import android.util.Log;
 
-import com.android.settings.R;
 import com.android.settings.Utils;
 import com.android.settings.core.PreferenceController;
 
@@ -37,8 +36,7 @@ public class SystemUpdatePreferenceController extends PreferenceController {
 
     private static final String TAG = "SysUpdatePrefContr";
 
-    static final String KEY_SYSTEM_UPDATE_SETTINGS = "system_update_settings";
-    static final String KEY_UPDATE_SETTING = "additional_system_update_settings";
+    private static final String KEY_SYSTEM_UPDATE_SETTINGS = "system_update_settings";
 
     private final UserManager mUm;
 
@@ -47,30 +45,33 @@ public class SystemUpdatePreferenceController extends PreferenceController {
         mUm = um;
     }
 
+    @Override
+    protected boolean isAvailable() {
+        return mUm.isAdminUser();
+    }
+
+    @Override
+    protected String getPreferenceKey() {
+        return KEY_SYSTEM_UPDATE_SETTINGS;
+    }
+
     @Override
     public void displayPreference(PreferenceScreen screen) {
-        if (isAvailable(mContext, KEY_SYSTEM_UPDATE_SETTINGS)) {
+        if (isAvailable()) {
             Utils.updatePreferenceToSpecificActivityOrRemove(mContext, screen,
                     KEY_SYSTEM_UPDATE_SETTINGS,
                     Utils.UPDATE_PREFERENCE_FLAG_SET_TITLE_TO_MATCHING_ACTIVITY);
         } else {
             removePreference(screen, KEY_SYSTEM_UPDATE_SETTINGS);
         }
-
-        if (!isAvailable(mContext, KEY_UPDATE_SETTING)) {
-            removePreference(screen, KEY_UPDATE_SETTING);
-        }
     }
 
     @Override
     public void updateNonIndexableKeys(List<String> keys) {
         // TODO: system update needs to be fixed for non-owner user b/22760654
-        if (!isAvailable(mContext, KEY_SYSTEM_UPDATE_SETTINGS)) {
+        if (!isAvailable()) {
             keys.add(KEY_SYSTEM_UPDATE_SETTINGS);
         }
-        if (!isAvailable(mContext, KEY_UPDATE_SETTING)) {
-            keys.add(KEY_UPDATE_SETTING);
-        }
     }
 
     @Override
@@ -87,21 +88,6 @@ public class SystemUpdatePreferenceController extends PreferenceController {
         return false;
     }
 
-    /**
-     * Whether a preference should be available on screen.
-     */
-    private boolean isAvailable(Context context, String key) {
-        switch (key) {
-            case KEY_SYSTEM_UPDATE_SETTINGS:
-                return mUm.isAdminUser();
-            case KEY_UPDATE_SETTING:
-                return context.getResources().getBoolean(
-                        R.bool.config_additional_system_update_setting_enable);
-            default:
-                return false;
-        }
-    }
-
     /**
      * Trigger client initiated action (send intent) on system update
      */