suspected range:
https://chromium.googlesource.com/chromium/src/+log/bae2319eb135aba1431b8dfb8f0ca00574bb0964%5E..bc3cd02ba801244f816ed9edf00b2e9bc40b60e3?pretty=fuller&n=

In this range, https://chromium.googlesource.com/chromium/src/+/bae2319eb135aba1431b8dfb8f0ca00574bb0964 this is the only change that looks changing mouse behaviors.

Let me assign the author, bsep@.

Yes, that was the offending commit. I could reproduce the issue on Linux locally which was fixed by reverting.

Reverted in https://chromium-review.googlesource.com/c/chromium/src/+/1016601

Thanks for the revert. I'll take a look before I re-land.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e35026faef6e203a3fb00d39ddf7df56bf6a3246

commit e35026faef6e203a3fb00d39ddf7df56bf6a3246
Author: Bret Sepulveda <bsep@chromium.org>
Date: Thu May 03 19:11:28 2018

Reland: Use the real mouse position when synthesizing mouse events.

Aura synthesizes a mouse event at certain times, including when the
window comes back from being minimized. Currently it uses the last known
mouse position, which works in most cases. However, the window doesn't
get mouse events when minimized, so the last known position isn't
updated. When the window comes back, if the user's mouse is not over the
window it can cause buttons to get stuck in the hovered state until the
user moves the mouse back into the window.

To fix this, this patch uses the real mouse position.

This patch also updates content_shell to move the mouse to 0,0 in
headless mode, to avoid any queries to the real mouse position from
interfering with blink tests. This patch also adds an implementation
for MoveCursorTo on Windows.

Bug:  828591 ,  834166 
Change-Id: I81354c77805c1928eb0cbccb900856a8c523709d
Reviewed-on: https://chromium-review.googlesource.com/1022959
Reviewed-by: Mike West <mkwst@chromium.org>
Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Commit-Queue: Bret Sepulveda <bsep@chromium.org>
Cr-Commit-Position: refs/heads/master@{#555843}
[modify] https://crrev.com/e35026faef6e203a3fb00d39ddf7df56bf6a3246/content/shell/browser/shell_views.cc
[modify] https://crrev.com/e35026faef6e203a3fb00d39ddf7df56bf6a3246/ui/aura/window_event_dispatcher.cc
[modify] https://crrev.com/e35026faef6e203a3fb00d39ddf7df56bf6a3246/ui/aura/window_event_dispatcher.h
[modify] https://crrev.com/e35026faef6e203a3fb00d39ddf7df56bf6a3246/ui/platform_window/win/win_window.cc