When deserializing an SkSL shader, it's possible to encounter code that
doesn't compile (particularly from the last year, when syntax tweaks
were being made). By default, we still treat this as an error and fail
to load the SKP. In the SKP debugger, though, we add a lenient mode that
permits these failures. If any of the children were SkShaders, we
instead return that. If all else fails, we just return nullptr, which
will cause the triggering draw to use a solid paint-color, but at least
allow the SKP to be loaded and viewed.
For color-filters and blenders, we allow malformed SkSL, but always
return nullptr.
The bug that prompted this change involved Android's overscroll stretch
shader, where this approach works particularly well (it turns the
stretch into a simple pass-through of the underlying content).
Change-Id: I756c694739d31b11efa1b82c126f34440a7de66a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/515543
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
0817ce7c5b