Fix string typing in generated code

Bug: skia:
Change-Id: Ifbccc6d6880522177ac7a0ae2183be64a3ebfe50
Reviewed-on: https://skia-review.googlesource.com/34681
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
4 files changed