I can repro fairly consistently but this is paint related and I don't really know how to debug this efficiently. Over to paint.

Is this related to crbug/825033?

*** Bulk Edit ***
M67 Stable promotion is coming soon. Your bug is labelled as Stable ReleaseBlock, pls make sure to land the fix and request a merge into the release branch ASAP. 

If fix is already merged to M67 and nothing else is pending, pls mark the bug as fixed. Thank you.

I am working on several regressions and wont be able to get to this soon. Chris, can you look at this one?

Reduced testcase attached. To reproduce:
1. Load the page
2. Scroll down to the bottom
3. Load again (will retain scroll offset)
4. Scroll back to top
5. Hover element.

Expected: changes background color to green
Actual: disappears

Deleted: test2.html 527 bytes

test2.html 527 bytes View Download

*** Bulk Edit ***
M67 Stable promotion is coming VERY soon. Your bug is labelled as Stable ReleaseBlock, pls make sure to land the fix and request a merge into the release branch ASAP. 

If fix is already merged to M67 and nothing else is pending, pls mark the bug as fixed. Thank you.

This bug is caused by the fact that the unclipped (and clipped) absolute bounding
box rects of PaintLayers incorrectly still include root scroll offset. This is a problem
because we should not cache anything that involves root scroll offset, since scroll
update should not require recomputing compositing inputs.

These rects are used for (a) overlap testing and (b) computation of squashing heuristics
for sparsity. Both use-cases were broken. Symptoms can include disappearing content
after scroll, since the overlap test gets confused about what overlaps what.

The fix is very simple, working on that now.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/7e3ce87568c3a2338775ededa458e273605da216

commit 7e3ce87568c3a2338775ededa458e273605da216
Author: Chris Harrelson <chrishtr@chromium.org>
Date: Wed May 09 19:37:29 2018

[RLS] Don't include scroll offset for unclipped absolute bounding boxes of PaintLayers.

Bug:  838811 
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Change-Id: I98804e49d7b50d7f192e54806a00669dc843a1ae
Reviewed-on: https://chromium-review.googlesource.com/1048970
Commit-Queue: Tien-Ren Chen <trchen@chromium.org>
Reviewed-by: Tien-Ren Chen <trchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#557280}
[modify] https://crrev.com/7e3ce87568c3a2338775ededa458e273605da216/third_party/blink/renderer/core/BUILD.gn
[modify] https://crrev.com/7e3ce87568c3a2338775ededa458e273605da216/third_party/blink/renderer/core/paint/compositing/compositing_inputs_updater.cc
[modify] https://crrev.com/7e3ce87568c3a2338775ededa458e273605da216/third_party/blink/renderer/core/paint/compositing/compositing_inputs_updater_test.cc
[modify] https://crrev.com/7e3ce87568c3a2338775ededa458e273605da216/third_party/blink/renderer/core/paint/compositing/compositing_requirements_updater.cc
[add] https://crrev.com/7e3ce87568c3a2338775ededa458e273605da216/third_party/blink/renderer/core/paint/compositing/compositing_requirements_updater_test.cc
[modify] https://crrev.com/7e3ce87568c3a2338775ededa458e273605da216/third_party/blink/renderer/core/paint/paint_layer.h

CL listed at #9 landed in trunk 57 mins back, Pls update the bug with canary result tomorrow. Thank you.

Also since this is regressed is M66 stable, how safe and critical is the merge for M67 which will be going to stable soon?

I think the bug will happen often, and on prominent pages (e.g. this bug tracks a regression
on an Amazon product page).

The fix is relatively safe, but on reflection I'd prefer to let it bake in Canary for a few
days before merge.

Thank you  chrishtr@. Pls update the bug with canary result on Friday or Monday morning if you like.

Verified the fix on the latest canary(68.0.3426.0) on Windows-10, Mac OS 10.13.3 and Linux Ubuntu 14.04 as per the test steps in C#0 and C#6. This seems to be working as intended hence adding the verified label.

This bug requires manual review: M67 has already been promoted to the beta branch, so this requires manual review
Please contact the milestone owner if you have questions.
Owners: cmasso@(Android), cmasso@(iOS), kbleicher@(ChromeOS), govind@(Desktop)

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

*** Bulk Edit ***
M67 Stable promotion is coming VERY soon. Your bug is labelled as Stable ReleaseBlock, pls make sure to land the fix and request a merge into the release branch ASAP. 

If fix is already merged to M67 and nothing else is pending, pls mark the bug as fixed. Thank you.

The NextAction date has arrived: 2018-05-14

I think the patch is ready to merge. Confirmed fixed on latest Canary,
and no other bugs have been reported related to it.

Approving merge to M67 branch 3396 based on comment #19. Please merge ASAP. Thank you.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/41b4e64e7b57d7ef7dba61c5168ec387b677820f

commit 41b4e64e7b57d7ef7dba61c5168ec387b677820f
Author: Chris Harrelson <chrishtr@chromium.org>
Date: Mon May 14 17:43:05 2018

[RLS] Don't include scroll offset for unclipped absolute bounding boxes of PaintLayers.

TBR=chrishtr@chromium.org

(cherry picked from commit 7e3ce87568c3a2338775ededa458e273605da216)

Bug:  838811 
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Change-Id: I98804e49d7b50d7f192e54806a00669dc843a1ae
Reviewed-on: https://chromium-review.googlesource.com/1048970
Commit-Queue: Tien-Ren Chen <trchen@chromium.org>
Reviewed-by: Tien-Ren Chen <trchen@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#557280}
Reviewed-on: https://chromium-review.googlesource.com/1057952
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Cr-Commit-Position: refs/branch-heads/3396@{#591}
Cr-Branched-From: 9ef2aa869bc7bc0c089e255d698cca6e47d6b038-refs/heads/master@{#550428}
[modify] https://crrev.com/41b4e64e7b57d7ef7dba61c5168ec387b677820f/third_party/blink/renderer/core/BUILD.gn
[modify] https://crrev.com/41b4e64e7b57d7ef7dba61c5168ec387b677820f/third_party/blink/renderer/core/paint/compositing/compositing_inputs_updater.cc
[modify] https://crrev.com/41b4e64e7b57d7ef7dba61c5168ec387b677820f/third_party/blink/renderer/core/paint/compositing/compositing_inputs_updater_test.cc
[modify] https://crrev.com/41b4e64e7b57d7ef7dba61c5168ec387b677820f/third_party/blink/renderer/core/paint/compositing/compositing_requirements_updater.cc
[add] https://crrev.com/41b4e64e7b57d7ef7dba61c5168ec387b677820f/third_party/blink/renderer/core/paint/compositing/compositing_requirements_updater_test.cc
[modify] https://crrev.com/41b4e64e7b57d7ef7dba61c5168ec387b677820f/third_party/blink/renderer/core/paint/paint_layer.h