GitLab

Currently, headless can dismiss beforeunload dialogs, but the target
page will still proceed to close since default implementation in content/
disregards BeforeUnload results: https://source.chromium.org/chromium/chromium/src/+/master:content/public/browser/web_contents_delegate.cc;l=64?q=BeforeUnloadFired%20f:content&ss=chromium%2Fchromium%2Fsrc

This patch changes this.

Change-Id: I2c1a04dde390dbb90ac8c547187405fa513d0723
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2516217
Commit-Queue: Andrey Lushnikov <lushnikov@chromium.org>
Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#823751}