Make sure GrResourceCache frees resources waiting on messages during destruction.

Bug: skia:6812
Change-Id: I86c50a9e301ae4846e638c915f94b797d60ee9a1
Reviewed-on: https://skia-review.googlesource.com/146646
Commit-Queue: Greg Daniel <egdaniel@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
4 files changed