Particles: remove non-stable random, add better enum reflection

The other generator was never used (or useful). String-based serialization
of enums is quite helpful, though.

Bug: skia:
Change-Id: Ic9d58f8d20cfe7aba47722bd74f1e6f8f0f219e5
Reviewed-on: https://skia-review.googlesource.com/c/195368
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
5 files changed