GN: make libwebp an optional dependency
This will be handy for folks who don't have libwebp, like Fuchsia.
I convinced myself that this is done right by:
- building in all three modes (default and explicitly set both ways);
- looking at verbose Ninja logs to see the presence/lack of SK_HAS_WEBP_LIBRARY;
- running dm -m Codec, which passes with libwebp and segfault without it.
If this is viable, I intend to make all third-party dependencies optional
and follow this pattern. :skia should link and degrade gracefully without
any of //third_party. It's okay for tools to have hard third-party
dependencies; we just need them to get past the `gn gen` stage without them.
BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2270693004
Review-Url: https://codereview.chromium.org/2270693004
1 file changed