Show the footer when global switch is off.

In the original implementation we showed a footer when global switch is off,
however, this was broken due to some refactor. This patch fixes the issue where
we don't set the visibility of the footer when global switch is on/off.

Bug: b/148626177
Test: make RunSettingsRoboTests ROBOTEST_FILTER=GraphicsDriver
Change-Id: I0f0763ee1551199cc8611c650350a2adbdf402ed

src/com/android/settings/development/graphicsdriver/GraphicsDriverFooterPreferenceController.java

@@ -26,6 +26,7 @@ import android.os.Looper;
 import android.provider.Settings;
 
 import androidx.annotation.VisibleForTesting;
+import androidx.preference.Preference;
 import androidx.preference.PreferenceScreen;
 
 import com.android.settings.core.BasePreferenceController;
@@ -79,6 +80,12 @@ public class GraphicsDriverFooterPreferenceController extends BasePreferenceCont
         mGraphicsDriverContentObserver.unregister(mContentResolver);
     }
 
+    @Override
+    public void updateState(Preference preference) {
+        final FooterPreference footerPref = (FooterPreference) preference;
+        footerPref.setVisible(isAvailable());
+    }
+
     @Override
     public void onGraphicsDriverContentChanged() {
         updateState(mPreference);