Hi omrillo@ and newcomer@, since I did the shelf items drag after showing context menu before, I just surprised that shelf items cannot be dragged now. Is this what we want now? Or it is a bug?

They should be draggable, I couldn't reproduce on 65.3325.65

Certainly a bug.

Re #4, yes, shelf items are draggable on 65, but not 66.

Hi newcomer@, this is a bug caused by the CL: https://chromium-review.googlesource.com/c/chromium/src/+/905864

The event stream for dragging is like: ET_GESTURE_TAP_DOWN->ET_GESTURE_TAP_CANCEL
->ET_GESTURE_SCROLL_BEGIN->ET_GESTURE_SCROLL_UPDATE->...
The drag should not be cancelled in ET_GESTURE_TAP_CANCEL.

I won't be in for a few days, so I'll leave the decision to revert it up to you. Probably best to revert :). I won't be able to make a better fix until I'm back (no touch devices to test with at home).

Yes, I agree, this bug seems to be more serious. I don't have a better solution either so I would revert it for now.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/848e45f8a9e64566cbda981573ceba68219b0e24

commit 848e45f8a9e64566cbda981573ceba68219b0e24
Author: Weidong Guo <weidongg@chromium.org>
Date: Thu Feb 15 17:15:14 2018

Revert "cros: Fix accidental enlargement of app icon on two finger tap."

This reverts commit 78a2d8249dead80d87b0e5a79481be7e579ae3b0.

Reason for revert: This causes  bug 812088 .

Original change's description:
> cros: Fix accidental enlargement of app icon on two finger tap.
> 
> Our logic assumed that an ET_GESTURE_END will always come
> after an ET_GESTURE_TAP_DOWN, this isn't true.
> 
> When a Two-finger tap (ET_GESTURE_TWO_FINGER_TAP) occurs the
> event stream is ET_GESTURE_TAP_DOWN -> ET_GESTURE_TAP_CANCEL ->
> ET_GESTURE_TWO_FINGER_TAP with no ET_GESTURE_END.
> 
> This CL fixes the issue by clearing the set state by ET_GESTURE_TAP_DOWN
> on ET_GESTURE_TAP_CANCEL.
> 
> Bug: 809751
> Change-Id: Iefeda869c70a75ba09a21fe4449b337a5cb7a826
> Reviewed-on: https://chromium-review.googlesource.com/905864
> Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
> Commit-Queue: Alex Newcomer <newcomer@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#534888}

TBR=xiyuan@chromium.org,newcomer@chromium.org

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

Bug: 809751, 812088 
Change-Id: Id0bfd6b52161df3b3dcf85ed384890ae11c2efb5
Reviewed-on: https://chromium-review.googlesource.com/920121
Reviewed-by: Weidong Guo <weidongg@chromium.org>
Commit-Queue: Weidong Guo <weidongg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#537055}
[modify] https://crrev.com/848e45f8a9e64566cbda981573ceba68219b0e24/ash/shelf/shelf_button.cc