GIMP 2.8 Python Plug-in.
This plug-in scales the contents of the layer (or layer group) to image size.
1. Extract "scale-layer-to-image-size.py" from .zip archive to the ".../.gimp-2.x/plug-ins/" directory.
2. Make sure that the extracted file is executable.
3. If you are already running GIMP, close and reopen it.