Bug 1209812 went a long way towards eliminating gfxImageFormat in favour of gfx::SurfaceFormat. Indeed, gfxImageFormat is now just a typedef of gfx::SurfaceFormat. However, there is still a subtle distinction relating to endian-ness that the functions SurfaceFormatToImageFormat() and ImageFormatToSurfaceFormat() demonstrate. On little-endian platforms, those functions are no-ops, but on big-endian platforms they are not. Some parts of the code expect one form, and some parts expect the other. So before we can get rid of the gfxImageFormat typedef, we should remove all the calls to these two functions so that all parts of the code expect the SurfaceFormat form.