The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d0d9e62436823911602eb0f09c8161a0b23dc918

commit d0d9e62436823911602eb0f09c8161a0b23dc918
Author: Scott Violet <sky@chromium.org>
Date: Fri Jan 05 00:56:57 2018

views: fix possible UAF in MenuButton

MenuButton::OnGestureEvent calls Activate(). Activate() may result in
deleting the MenuButton. Activate() deals with this, but not
OnGestureEvent(). This fixs OnGestureEvent() to early out if the
MenuButton is destroyed.

BUG= 799296 
TEST=covered by test

Change-Id: Icdfc4be9caa3dab12d337d98343365257e5e587d
Reviewed-on: https://chromium-review.googlesource.com/851070
Reviewed-by: Elliot Glaysher <erg@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#527177}
[modify] https://crrev.com/d0d9e62436823911602eb0f09c8161a0b23dc918/ui/views/controls/button/menu_button.cc
[modify] https://crrev.com/d0d9e62436823911602eb0f09c8161a0b23dc918/ui/views/controls/button/menu_button.h
[modify] https://crrev.com/d0d9e62436823911602eb0f09c8161a0b23dc918/ui/views/controls/button/menu_button_unittest.cc