How is the post process color tint calculated?

How is the post process color tint calculated (specifically for the mobile tone mapper)? If I create a post process material and multiply the scene color by the tint color, I get different results compared to when I set the tint value in the mobile tonemapper section of the post process volume. I’ve looked through the shaders (PostProcessMobile.usf, PostProcessTonemap.usf, TonemapCommon.ush), but the only relevant calculation I’ve found is in PostProcessTonemap.usf at line 458:

half3 LinearColor = SceneColor.rgb * ColorScale0.rgb;

I think ColorScale0 is supposed to be SceneColorTint.rgb. Does anyone know why I’m getting different results with my manual calculation? I need to manually tint the screen to allow for cameras that are partially submerged underwater.