Could you use "document" instead of "window"? I think that is what you want.
See https://bugs.chromium.org/p/chromium/issues/detail?id=569707.

Nit: e.path is no longer recommended. If we can assume that chrome is >= 53, you should use e.composedPath(), instead of e.path.

I'm afraid that it might be unclear how event path should be on `window` in DOM Standard.
Let me re-check it, and file an issue for the spec, if necessary.

In any case, you can avoid an issue by registering event listener on document, instead of window.

document doesn't work because there might be a event handler on the document that calls preventDefault, in which case, we wouldn't want to navigate the page.

With my web developer hat on, it's very confusing that registering the listener on the window and document does different things.

I agree that it's confusing that window and document do different things.

I think we might want to *revert* the conclusion of:
https://bugs.chromium.org/p/chromium/issues/detail?id=569707

Let me update the spec, DOM Standard, at first, then try to fix Blink's implementation too.

Do you have any timeline? Is this urgent?

I don't know how urgent this is. Pam?

I think it can wait for you to update the spec first. 

Okay. Let me add this task to my backlog.

PR for DOM Standard is on-going: https://github.com/whatwg/dom/pull/327

I have updated the DOM Standard to clarify how e.path should be in an event listener on window.

The remaining task is to update Blink's implementation.

Well, as Ojan proposed, the current workaround of using activeElement is likely to cover most cases, and certainly better than what the backspace extension is doing right now. So no huge urgency.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/92dd0aa2f5587f380f7f8f7c58d1f9a9862e3254

commit 92dd0aa2f5587f380f7f8f7c58d1f9a9862e3254
Author: hayato <hayato@chromium.org>
Date: Mon Oct 03 04:03:34 2016

Make event.composedPath() on window behave the same way as that on document

The spec is: https://dom.spec.whatwg.org/#dom-event-composedpath
The relevant change of the spec: https://github.com/whatwg/dom/pull/327

I have updated the DOM Standard to clarify the behavior of event.composedPath() on
window.

The current Blink's implementation of event.composedPath() on window returns
just [window]. Now, event.composedPath() on window behaves the same way as that on document.

BUG= 645527 

Review-Url: https://codereview.chromium.org/2343923003
Cr-Commit-Position: refs/heads/master@{#422368}

[modify] https://crrev.com/92dd0aa2f5587f380f7f8f7c58d1f9a9862e3254/third_party/WebKit/LayoutTests/shadow-dom/event-composed-path.html
[modify] https://crrev.com/92dd0aa2f5587f380f7f8f7c58d1f9a9862e3254/third_party/WebKit/Source/core/events/Event.cpp
[modify] https://crrev.com/92dd0aa2f5587f380f7f8f7c58d1f9a9862e3254/third_party/WebKit/Source/core/events/EventPath.cpp
[modify] https://crrev.com/92dd0aa2f5587f380f7f8f7c58d1f9a9862e3254/third_party/WebKit/Source/core/events/EventPath.h