Preserve color space of images in deferred texture API

For raster images, this already worked (we were peeking the
pixmap's info). But for generated images, we discarded
format and color space information. Fixes an error with the
deferred GMs in sRGB modes, and also should help the Chrome
color correctness work.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2416453004

Review-Url: https://codereview.chromium.org/2416453004
1 file changed