Please specify the operating system and (if Chrome OS, which I'm assuming it is) the device.

Seems like the same issue I reported in  Issue 594840 .

Yes, this is Chrome OS and these are the same bug

 Issue 594840  has been merged into this issue.

This seems to be happening on higher resolution devices (I can repro on samus and lulu).

oshima@ could this be related to device scale changes?

It wasn't enabled on 49, so it's not related if it's really happening since 49. On 51, I'm seeing similar behavior even when I disable the device scale change.

Note that there was recent changes in scrolling, smooth scrolling and scrolling speed. (I think matt was involved in it?)

I'm getting touchscreen jitters on web page scrolling too. This looks like an issue with scroll handling rather than the app list.

This is a bit confusing because there seem to be separate issues for touchscreen and touchpad.

We can't repro any jittering issues for touchpad but we did find the app list was quite over-sensitive to touchpad gestures for scrolling. We might address that as low-priority.

The touch screen does jitter a lot though, but as Chris said, this affects all scroll surfaces, not jut app list, so I filed a new bug on input:  Issue 596357 .

mgiuca@ what are we tracking in this bug?

I'm not really sure. I think there are two issues: jittering on touch screen (covered by  Issue 596357 ) and hyper-sensitive touch pad (no bug filed yet). I think we should file a new bug for that and close this, but there is still the unreproducible original issue of jittery touch pad.

I'm on vacation now so I can't look at this. Calamity to triage.

I'm happy to keep this bug for the touchpad problem. I can reproduce the touchpad jittering.

This problem also appears on daisy devices suggesting it's not a problem with the Pixel's input event handling.

I'm happy to keep this bug for the touchpad problem. I can reproduce the touchpad jittering.

This problem also appears on daisy devices suggesting it's not a problem with the Pixel's input event handling. It may be that we just need to increase the threshold for the touch scrolling here.

calamity@ do you have a CL to fix the issue with the solution you suggested above?

I can't actually test the fix until I figure out how to reproduce the issue on a dev build. There's a constant that I could just change, but I don't know what a good number is without some trial and error.

Fair. kathrelkeld@ can you please help repro on a dev build?

Confirmed with calamity@ that by dev build he means developer build, not dev mode build.  We don't use developer builds on my team, so he's on his own there.

He is finding someone else on his team to take this before he goes OOO

calamity@ does this still ring as a stable blocker for M50?

Nope. This has been around for a long time. The touchscreen issue was new, but that's in another bug now.

 Issue 616133  has been merged into this issue.

calamity@ any thoughts here? This is still pretty chunky in 53.

If you want a way to repro this, you can install a chromeos image from https://cros-goldeneye.corp.google.com/  I believe any of the latest images on your favorite device will repro the problem.

I need a repro on a debug build so I can see exactly what's happening with the events though. I can definitely repro on my stable Chromebook, it's just that I can't figure it out without a debug build to see what's happening with the scroll events.

I may be able to plug a touchpad into my machine but I'm not sure if the Linux ChromeOS will exhibit the same behavior...

Are you not able to access the goldeneye site?  There are test images there for your favorite devices that you should be able to install.  In the worst case you can do your own test build and install on a chromeos device.  Are you not able to do that for some reason?

#25 It needs to be a debug build that he can insert his own logging into. Theoretically you could build your own image onto a Chrome OS device but that's a lot of effort to go to. (We are not on the Chrome OS team so we don't do this thing normally.)

Did we resolve the need for machines / builds? Any help needed on this?

I have a speculative fix landing. It fixes the issue on a linux laptop we tried.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4db974d7763416334efdbe4859427475ff5889f9

commit 4db974d7763416334efdbe4859427475ff5889f9
Author: calamity <calamity@chromium.org>
Date: Fri Jun 03 05:43:02 2016

Add scroll threshold for app list for mouse wheel events.

This CL fixes an issue with touchpad events being read as mousewheel
events and causing jank on touchpad scroll in the app list. Instead of
figuring out the whole stack and why the wrong event is coming in, just
use the scroll threshold everywhere.

BUG= 594264 

Review-Url: https://codereview.chromium.org/2029993002
Cr-Commit-Position: refs/heads/master@{#397642}

[modify] https://crrev.com/4db974d7763416334efdbe4859427475ff5889f9/ui/app_list/pagination_controller.cc

Verified on  8477.0.0, 53.0.2768.0