Return SkGlyphCache and GrTextStrike together.

This is the first step of making a wrapper class to keep these two caches
in sync.

Change-Id: I84ef408a31a77074191a60c8b5943ededcd306b7
Reviewed-on: https://skia-review.googlesource.com/c/180375
Commit-Queue: Herb Derby <herb@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
3 files changed