Where are Conversion codes from BaseColor to SceneColor at Lighting in Engine source?

I would like to read the source code of conversion from BaseColor to SceneColor in Lingting processes.
Where are these codes in Eingine source code ?

The codes are host-side codes wirtten in C. (.cpp) or GPU-side code in shader (.usf)?
I read code from FDeferredShadingSceneRenderer::Render, but I didn’t find the places in souce code.

Thanks so much in advance guys.