Fixes theme choice on boot when scheme is not from latest wallpaper.

Color theme was getting reset on reboot if the theme was based on a
wallpaper that was not the most recently set (e.g., based on lock screen
wallpaper when the home screen wallpaper had been set later on). This
applied to both static and live wallpapers.

Fixes: 229406616
Fixes: 234603929
Test: TreeHugger passes
Change-Id: I325e3fae9be8f56b13393320171e78ccffeea249