NOTE: Unable to provide bisect using bisect-per-revision script as tab is getting crashed after launching the Chrome builds from tool. Hence providing bisect using old script.

You are probably looking for a change made after 523680 (known good), but no later than 523691 (first known bad).
CHANGELOG URL:
  https://chromium.googlesource.com/chromium/src/+log/48b444dd6b57a1937ffe86f3a1399fdd2adae254..537399fd2bf3faa258c7b2c4f526681ed8f4a4b3

Suspect: https://chromium.googlesource.com/chromium/src/+/12dca8659ca7a447e813d0d25f930cf7932b87fd

@chaopeng: Kindly help to reassign, if your changes are not related to this issue.

Adding RB Label as this is a recent Regression. Please remove if not required.
Thank You.

Confirmed this issue is from my CL. reverting.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ffe75f56318e0e3c2f29ee0a1156c85f83dfad2e

commit ffe75f56318e0e3c2f29ee0a1156c85f83dfad2e
Author: Jianpeng Chao <chaopeng@chromium.org>
Date: Fri Dec 15 19:22:35 2017

Revert "Fix Windows touchpad lagging in first tab"

This reverts commit 12dca8659ca7a447e813d0d25f930cf7932b87fd.

Reason for revert:  crbug.com/795223 

Original change's description:
> Fix Windows touchpad lagging in first tab
>
> Currently the receiving of WM_MOUSEWHEEL messages lags when we open a
> URL on a new window until we resize. The issue was introduced by
> r384698. That CL change wait for MOUSE_EVENT to wait for SENDMESSAGE
> in MessagePumpForUI::WaitForWork to optimize the GPU thread. But the
> GPU thread does not use MessagePumpForUI anymore so it should be OK to
> just remove that code.
>
> The updated version of Chrome was tested to make sure that the hangs
> that were occasionally seen when using chrome://tracing are still gone.
>
> After this CL chaopeng@ need to monitor to make sure that the crash
> rate not increase.
>
> Bug:  713907 , 596190
> Change-Id: I7545a867de4851acd4e57c9b8c7a3dd05def1dd8
> Reviewed-on: https://chromium-review.googlesource.com/809829
> Commit-Queue: Jianpeng Chao <chaopeng@chromium.org>
> Reviewed-by: Bruce Dawson <brucedawson@chromium.org>
> Reviewed-by: Lei Zhang <thestig@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#523689}

TBR=thestig@chromium.org,brucedawson@chromium.org,chaopeng@chromium.org

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

Bug:  713907 , 596190,  795223 
Change-Id: I3f53fd77e7a6545cd214444cac46709cff0142c9
Reviewed-on: https://chromium-review.googlesource.com/830174
Commit-Queue: Jianpeng Chao <chaopeng@chromium.org>
Reviewed-by: Jianpeng Chao <chaopeng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#524428}
[modify] https://crrev.com/ffe75f56318e0e3c2f29ee0a1156c85f83dfad2e/base/message_loop/message_pump_win.cc

I check spyxx with my CL, the mouse button down/up are route to correct window.

Update:-
 Tested this issue on Windows (7,8,10) machines using latest Chrome canary build# 65.0.3298.0 and fix is working as expected i.e. Copies count decreases/increases properly according to the click. Hence adding TE Verified labels. 

Please find the attached screen-cast for reference.

Thanks..!

Deleted: LatestCanary Behavior.mp4 1.1 MB

	LatestCanary Behavior.mp4 1.1 MB View Download

The new approach of 713907, 596190 does not effect print page. Close this issue.