/usr/share/themes/Bluebird/metacity-1/metacity-theme-1.xml is in shimmer-themes 1.3.0-0ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 | <!-- This is an intentionally empty file, placed here just to satisfy GNOME Appearance Properties.
The actual theme is located in metacity-theme-2.xml -->
|