The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d2d91c0898fdf1feec4e335d25932da4de28bdf4

commit d2d91c0898fdf1feec4e335d25932da4de28bdf4
Author: Lucas Furukawa Gadani <lfg@chromium.org>
Date: Fri Jun 02 22:14:23 2017

Add DCHECKS to prevent incorrect construction of WebMouseEvent.

Bug:  718079 
Change-Id: I2f315038d0fb748d5c770daad9ed335b3cb1b364
Reviewed-on: https://chromium-review.googlesource.com/517730
Commit-Queue: Lucas Furukawa Gadani <lfg@chromium.org>
Reviewed-by: David Tapuska <dtapuska@chromium.org>
Reviewed-by: Nasko Oskov <nasko@chromium.org>
Reviewed-by: Rick Byers <rbyers@chromium.org>
Cr-Commit-Position: refs/heads/master@{#476813}
[modify] https://crrev.com/d2d91c0898fdf1feec4e335d25932da4de28bdf4/content/browser/renderer_host/render_widget_host_impl.cc
[modify] https://crrev.com/d2d91c0898fdf1feec4e335d25932da4de28bdf4/third_party/WebKit/Source/platform/WebMouseEvent.cpp
[modify] https://crrev.com/d2d91c0898fdf1feec4e335d25932da4de28bdf4/third_party/WebKit/public/platform/WebMouseEvent.h