Add sk_InstanceID

Bug: skia:
Change-Id: I79b0dce96d9af7632f027afa5317a7725e96cda3
Reviewed-on: https://skia-review.googlesource.com/59861
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
5 files changed