GitLab

This reverts commit 86ff51d4.

Reason for revert: crbug.com/871587

Original change's description:
> Add ChildMediaLog.
> 
> Users of MediaLog have to be careful about the lifetime of the
> object, since it's passed around as a raw ptr.  For things like
> VdaVideoDecoder, which operate on multiple threads, it requires
> special care that the log isn't used after VdaVideoDecoder is
> no longer allowed to use it.
> 
> ChildMediaLog wraps a MediaLog, and provides an atomic way to
> prevent access to the underlying MediaLog.  For example,
> VdaVideoDecoder can do this when it's Destroy()ed, which is when it
> must stop using the MediaLog that it was given.  Additional calls
> to ChildMediaLog will do nothing.
> 
> The ChildMediaLog itself can be kept around until the other thread
> is definitely done using it.
> 
> 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: If350b2b78da96bf7ba844f582a96661fd0b15ef0
> Reviewed-on: https://chromium-review.googlesource.com/1139219
> Commit-Queue: Frank Liberato <liberato@chromium.org>
> Reviewed-by: Dan Sanders <sandersd@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#580952}

TBR=sandersd@chromium.org,liberato@chromium.org

Change-Id: Ic7457f610907c8e7d89fd26090b815d281b19664
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
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
Reviewed-on: https://chromium-review.googlesource.com/1164130Reviewed-by: Max Moroz <mmoroz@chromium.org>
Commit-Queue: Max Moroz <mmoroz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#581109}