Clean FooterPreferenceMixin and FooterPreferenceMixinCompat

Fixes: 124129485
Test: manual test
Test: make RunSettingsRoboTests ROBOTEST_FILTER=com.android.settings.core
Test: make RunSettingsRoboTests ROBOTEST_FILTER=com.android.settings.SettingsPreferenceFragmentTest
Test: make RunSettingsRoboTests ROBOTEST_FILTER=com.android.settings.bluetooth
Change-Id: I920d0de403b9c7109de0e2e53be7ed99bc8e7390

res/xml/night_display_settings.xml

@@ -58,7 +58,6 @@
         android:title="@string/night_display_text"
         android:selectable="false"
         settings:allowDividerAbove="true"
-        settings:searchable="false"
         settings:controller="com.android.settings.display.NightDisplayFooterPreferenceController"/>
 
 </PreferenceScreen>

src/com/android/settings/SettingsPreferenceFragment.java

@@ -53,7 +53,6 @@ import com.android.settings.widget.LoadingViewController;
 import com.android.settingslib.CustomDialogPreferenceCompat;
 import com.android.settingslib.CustomEditTextPreferenceCompat;
 import com.android.settingslib.core.instrumentation.Instrumentable;
-import com.android.settingslib.widget.FooterPreferenceMixinCompat;
 import com.android.settingslib.widget.LayoutPreference;
 
 import java.util.UUID;
@@ -68,10 +67,6 @@ public abstract class SettingsPreferenceFragment extends InstrumentedPreferenceF
 
     private static final String SAVE_HIGHLIGHTED_KEY = "android:preference_highlighted";
 
-    protected final FooterPreferenceMixinCompat mFooterPreferenceMixin =
-            new FooterPreferenceMixinCompat(this, getSettingsLifecycle());
-
-
     private static final int ORDER_FIRST = -1;
 
     private SettingsDialogFragment mDialogFragment;
@@ -317,8 +312,7 @@ public abstract class SettingsPreferenceFragment extends InstrumentedPreferenceF
         if (getPreferenceScreen() != null) {
             final View listContainer = getActivity().findViewById(android.R.id.list_container);
             boolean show = (getPreferenceScreen().getPreferenceCount()
-                    - (mHeader != null ? 1 : 0)
+                    - (mHeader != null ? 1 : 0)) <= 0
-                    - (mFooterPreferenceMixin.hasFooter() ? 1 : 0)) <= 0
                     || (listContainer != null && listContainer.getVisibility() != View.VISIBLE);
             mEmptyView.setVisibility(show ? View.VISIBLE : View.GONE);
         } else {

src/com/android/settings/bluetooth/BluetoothDetailsMacAddressController.java

@@ -32,7 +32,7 @@ import com.android.settingslib.widget.FooterPreference;
 public class BluetoothDetailsMacAddressController extends BluetoothDetailsController {
     public static final String KEY_DEVICE_DETAILS_FOOTER = "device_details_footer";
 
-    FooterPreference mFooterPreference;
+    private FooterPreference mFooterPreference;
 
     public BluetoothDetailsMacAddressController(Context context,
             PreferenceFragmentCompat fragment,