Make custom theme remeber selections while system config changes and then restore

Issue description is in b/157631127
Video: https://drive.google.com/file/d/1Ys8W1NwcmL5xt7UsGR0KmmPrub_cJVfx/view?usp=sharing

Also fix the gone preview issue:
Before https://drive.google.com/file/d/1y4mxcbatbeykqiMb6UuekrIiC5jYlNRT/view?usp=sharing
After https://drive.google.com/file/d/1nQ-4qIzpvecfAyM31hamKTnPI5QNWwr2/view?usp=sharing

Test: Manually
Bug: 157631127
Change-Id: I39d7040bba0b550119eb7088711502387d6ec82e