Remove obsolete image codec colorspace hacks.

With Herb's latest change, the codecs themselves are emitting images
tagged based on the new (separate) global flag. All of the changes we
had here to fixup color profile type are no longer needed (and just
create more confusion). This change effectively reverts the file to
where it was two commits ago.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1904943003

Review URL: https://codereview.chromium.org/1904943003
1 file changed