Simplify lifetime of scaler context for remote cache

Change-Id: Id51062e9b6231ae9eeabdc418adda8cc3974dcc3
Reviewed-on: https://skia-review.googlesource.com/149041
Commit-Queue: Herb Derby <herb@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
3 files changed