fix for persistent shader cache

Bug: skia:
Change-Id: I43b4dc58ab4dde3fa8140de0d73134c38f7d79db
Reviewed-on: https://skia-review.googlesource.com/140566
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
4 files changed