Patch lgtm, but let's re-enable in about a week. Is that enough numbers, CHECKs for us to debug the problem?

Yes. I think a week should be enough to inspect the UKM logs and ensure sanity of the data.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9bbdf45e7f766b1021a2fba39e98a746d356e681

commit 9bbdf45e7f766b1021a2fba39e98a746d356e681
Author: Khushal <khushalsagar@google.com>
Date: Tue Apr 17 23:00:35 2018

cc: Disable checker-imaging for decode=async tag.

Temporarily disabling checkering of decode=async tag images to debug
entries in ukm logs for checkerboarded images in the control group for
checkerimaging finch study.

R=vmpstr@chromium.org

Bug:  833666 
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: Ib9a79262599efa17fd18e9cb71d7518492e9a7ee
Reviewed-on: https://chromium-review.googlesource.com/1014644
Reviewed-by: vmpstr <vmpstr@chromium.org>
Commit-Queue: Khushal <khushalsagar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#551513}
[modify] https://crrev.com/9bbdf45e7f766b1021a2fba39e98a746d356e681/cc/tiles/checker_image_tracker.cc
[modify] https://crrev.com/9bbdf45e7f766b1021a2fba39e98a746d356e681/cc/trees/layer_tree_host_impl.cc

The NextAction date has arrived: 2018-04-24

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d0d02d99521d9067c9cbdc3658b2580b4d4b8c1c

commit d0d02d99521d9067c9cbdc3658b2580b4d4b8c1c
Author: Khushal <khushalsagar@chromium.org>
Date: Thu Apr 26 00:12:27 2018

Revert "cc: Disable checker-imaging for decode=async tag."

This reverts commit 9bbdf45e7f766b1021a2fba39e98a746d356e681.

Reason for revert: The patch verified that the reporting is accurate, no
crashes were introduced from the added CHECKs. And we have enough data
to check the UKM logs.

Original change's description:
> cc: Disable checker-imaging for decode=async tag.
> 
> Temporarily disabling checkering of decode=async tag images to debug
> entries in ukm logs for checkerboarded images in the control group for
> checkerimaging finch study.
> 
> R=​vmpstr@chromium.org
> 
> Bug:  833666 
> Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;master.tryserver.blink:linux_trusty_blink_rel
> Change-Id: Ib9a79262599efa17fd18e9cb71d7518492e9a7ee
> Reviewed-on: https://chromium-review.googlesource.com/1014644
> Reviewed-by: vmpstr <vmpstr@chromium.org>
> Commit-Queue: Khushal <khushalsagar@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#551513}

TBR=vmpstr@chromium.org,khushalsagar@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug:  833666 
Change-Id: I3425d7a7b4cc6d57ec26fee7ddee8827e97992dd
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;master.tryserver.blink:linux_trusty_blink_rel
Reviewed-on: https://chromium-review.googlesource.com/1029090
Reviewed-by: Khushal <khushalsagar@chromium.org>
Commit-Queue: Khushal <khushalsagar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553837}
[modify] https://crrev.com/d0d02d99521d9067c9cbdc3658b2580b4d4b8c1c/cc/tiles/checker_image_tracker.cc
[modify] https://crrev.com/d0d02d99521d9067c9cbdc3658b2580b4d4b8c1c/cc/trees/layer_tree_host_impl.cc