vjvalenti: What apps are you using? Would it be possible for you to upload a screencast?

weidongg: DO you think [1] would have fixed this?

[1] https://chromium-review.googlesource.com/c/chromium/src/+/1300215

Yes, it seems to have the same root cause.

I made a video of myself recreating the issue:

https://youtu.be/z_pij5HiC9g

Was this actually fixed? I can still recreate this issue in today's updated Beta.

re #7 - What version are you using? If it isn't higher than or equal to 72.0.3593.0 then the speculated change wouldn't be in.

It is fixed by https://chromium-review.googlesource.com/c/chromium/src/+/1308042 which was landed yesterday. Maybe it is not in today's beta channel yet.

I see. Would that mean that this could remain an issue for the Beta channel until 72 reaches Beta, i.e. around 6 weeks from now?

We have new beta version for 71 every day, hopefully the fix will be in tomorrow's build.

Thank you. I wouldn't even press further were it not a fairly serious issue!

Thanks for filing the bug, I just flash the lastest beta, it already has the fix for the similar bug, but I just managed to repro the issue in this bug, so reopen it for investigation.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/20236661c49fde434f56c6dd184775ad7314ec1b

commit 20236661c49fde434f56c6dd184775ad7314ec1b
Author: Weidong Guo <weidongg@chromium.org>
Date: Thu Nov 01 16:17:11 2018

Fix home launcher freeze issue after two finger drag

Enable auto-hide shelf. Drag from bottom bezel to show home launcher
and, meanwhile, use second finger to drag on home launcher, the launcher
freezes.

It happens because shelf is hidden when dragging with second finger
which prevents the drag end event reaching home gesture handler.

Changes:
1. Remove shelf visibility check for drag end event.
2. Avoid processing drag event when animation is running.

Bug:  899554 
Change-Id: I18262f813ab4acaab9266b7fba1c7790275d8fbc
Reviewed-on: https://chromium-review.googlesource.com/c/1311840
Reviewed-by: Sammie Quon <sammiequon@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Weidong Guo <weidongg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#604608}
[modify] https://crrev.com/20236661c49fde434f56c6dd184775ad7314ec1b/ash/app_list/home_launcher_gesture_handler.cc
[modify] https://crrev.com/20236661c49fde434f56c6dd184775ad7314ec1b/ash/app_list/home_launcher_gesture_handler.h
[modify] https://crrev.com/20236661c49fde434f56c6dd184775ad7314ec1b/ash/shelf/shelf_layout_manager.cc

This CL is tested manually on ToT.

Hmm. If you see the video I posted, I was able to trigger the bug using one finger. I don't know if that affects your patch, but I just wanted to clarify that.

re #16 - We were also able to trigger the bug with one finger, but its much easier with two. We have had similar bugs in the past with a single finger dispatching multi touch events, so we are quite certain that the patch in c#14 will fix your issue as well.

One finger swipe sometimes can be detected as two fingers by the sensor. I think that's why the issue is reproducible with one finger occationally, but always occurs with two fingers.

I see. That makes sense why I wasn't always able to trigger it. Thanks for following up!

Approving merge to M71 Chrome OS.  Thanks for the comments on #15

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/094d5bcca881303fc024c33c6185c9eb703b7730

commit 094d5bcca881303fc024c33c6185c9eb703b7730
Author: Weidong Guo <weidongg@chromium.org>
Date: Thu Nov 01 19:55:36 2018

Merge to M71: Fix home launcher freeze issue after two finger drag

Enable auto-hide shelf. Drag from bottom bezel to show home launcher
and, meanwhile, use second finger to drag on home launcher, the launcher
freezes.

It happens because shelf is hidden when dragging with second finger
which prevents the drag end event reaching home gesture handler.

Changes:
1. Remove shelf visibility check for drag end event.
2. Avoid processing drag event when animation is running.

Bug:  899554 
Change-Id: I18262f813ab4acaab9266b7fba1c7790275d8fbc
Reviewed-on: https://chromium-review.googlesource.com/c/1311840
Reviewed-by: Sammie Quon <sammiequon@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Weidong Guo <weidongg@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#604608}(cherry picked from commit 20236661c49fde434f56c6dd184775ad7314ec1b)
Reviewed-on: https://chromium-review.googlesource.com/c/1313413
Reviewed-by: Weidong Guo <weidongg@chromium.org>
Cr-Commit-Position: refs/branch-heads/3578@{#457}
Cr-Branched-From: 4226ddf99103e493d7afb23a4c7902ee496108b6-refs/heads/master@{#599034}
[modify] https://crrev.com/094d5bcca881303fc024c33c6185c9eb703b7730/ash/app_list/home_launcher_gesture_handler.cc
[modify] https://crrev.com/094d5bcca881303fc024c33c6185c9eb703b7730/ash/app_list/home_launcher_gesture_handler.h
[modify] https://crrev.com/094d5bcca881303fc024c33c6185c9eb703b7730/ash/shelf/shelf_layout_manager.cc

The following revision refers to this bug: 
https://chromium.googlesource.com/chromium/src.git/+/094d5bcca881303fc024c33c6185c9eb703b7730

Commit: 094d5bcca881303fc024c33c6185c9eb703b7730
Author: weidongg@chromium.org
Commiter: weidongg@chromium.org
Date: 2018-11-01 19:55:36 +0000 UTC

Merge to M71: Fix home launcher freeze issue after two finger drag

Enable auto-hide shelf. Drag from bottom bezel to show home launcher
and, meanwhile, use second finger to drag on home launcher, the launcher
freezes.

It happens because shelf is hidden when dragging with second finger
which prevents the drag end event reaching home gesture handler.

Changes:
1. Remove shelf visibility check for drag end event.
2. Avoid processing drag event when animation is running.

Bug:  899554 
Change-Id: I18262f813ab4acaab9266b7fba1c7790275d8fbc
Reviewed-on: https://chromium-review.googlesource.com/c/1311840
Reviewed-by: Sammie Quon <sammiequon@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Weidong Guo <weidongg@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#604608}(cherry picked from commit 20236661c49fde434f56c6dd184775ad7314ec1b)
Reviewed-on: https://chromium-review.googlesource.com/c/1313413
Reviewed-by: Weidong Guo <weidongg@chromium.org>
Cr-Commit-Position: refs/branch-heads/3578@{#457}
Cr-Branched-From: 4226ddf99103e493d7afb23a4c7902ee496108b6-refs/heads/master@{#599034}

Issue 896866 has been merged into this issue.