dpapad -- Can you take a look at this, and reassign if appropriate?  It causes a browser crash.

I repro'd this on mac, on both canary (.8) and stable (54.0.2840.71).
Stable crash: https://crash.corp.google.com/browse?stbtiq=f08d3b7900000000

I'm assuming this not an problem with url::Parsed, but instead with settings::StartupPagesHandler::HandleEditStartupPage() since it may be accessing a URL that not longer exists.

Does it also happen on the old Options page (I think you can still get to it on canary at chrome://settings-frame)?

No I don't see any crash on the old options page (chrome://settings).

This issue is a security regression. If you are not able to fix this quickly, please revert the change that introduced it.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Given that MD Settings has not shipped (not even to Dev), should this be a RB for beta?

FYI, candidate fix is at https://codereview.chromium.org/2477693005.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/05f574e9836e8345bbb59f9b828bf2d773331f82

commit 05f574e9836e8345bbb59f9b828bf2d773331f82
Author: dpapad <dpapad@chromium.org>
Date: Tue Nov 08 01:08:52 2016

MD Settings: Close edit startup URL dialog, if underlying URL list changes.

BUG= 661867 
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2477693005
Cr-Commit-Position: refs/heads/master@{#430455}

[modify] https://crrev.com/05f574e9836e8345bbb59f9b828bf2d773331f82/chrome/browser/resources/settings/on_startup_page/startup_urls_page.html
[modify] https://crrev.com/05f574e9836e8345bbb59f9b828bf2d773331f82/chrome/browser/resources/settings/on_startup_page/startup_urls_page.js
[modify] https://crrev.com/05f574e9836e8345bbb59f9b828bf2d773331f82/chrome/test/data/webui/settings/startup_urls_page_test.js
[modify] https://crrev.com/05f574e9836e8345bbb59f9b828bf2d773331f82/ui/webui/resources/cr_elements/cr_scrollable_behavior.js

Changing to type Bug as the panel didn't this was exploitable

This bug has been closed for more than 14 weeks. Removing security view restrictions.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot