Fix GrThreadSafeCache's abandonContext behavior

We need to abandon all the GPU resources before dropping any
refs the thread-safe cache may be holding.

Change-Id: Id1a06adf9e0241bfaf55e3f58bf8c2db928ea141
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/331536
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
2 files changed