IccProfile
The part of an ICC profile a document reader actually needs: the matrix/TRC shape that RGB and grey profiles use.
An ICC profile says how a file's numbers map to real colour. Ignoring it is what makes a photo tagged AdobeRGB look flat when it is drawn as if it were sRGB. This reads the tone curves and the colorant matrix, which is all a matrix/TRC profile has, and converts through XYZ.
Profiles that describe themselves with lookup tables (A2B0, mft1, mft2, mAB) are not read: parse returns null and the caller keeps its device-colour fallback. Those are mostly CMYK press profiles, where the device fallback is already what every other reader shows.
Properties
1 for grey, 3 for RGB.
True when this profile IS sRGB (or near enough), so converting through it would only add rounding. Most PDFs tag their colours "sRGB IEC61966-2.1", and for those the honest transform is no transform: the round trip through XYZ costs about a level of 0..255 and buys nothing.
Functions
Convert components (0..1 per channel) to sRGB.