[media] Prevent same-thread optimizations after VdaVideoDecoder::Destroy().

If the parent thread is the same as the gpu thread, these tests were
incorrect, allowing work to be done after Destroy(). Now that Windows is
running the media InterfaceFactory on the GPU main thread, this causes
use-after-free of |media_log_|.

Bug: 868760
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
Change-Id: I70dbeafe6744f721ef0eb407f43481095b7df3a5
Reviewed-on: https://chromium-review.googlesource.com/1155469
Reviewed-by: Frank Liberato <liberato@chromium.org>
Commit-Queue: Dan Sanders <sandersd@chromium.org>
Cr-Commit-Position: refs/heads/master@{#579177}
1 file changed