1299269 - Cross process navigations break the window object [cross-origin]

Status: NEW

(Core :: DOM: Content Processes, defect, P3)

Description

[Nika Layzell [:nika] (ni? for response)]

Attachment: openawindow.html

STR:
    1. Open the attached HTML document in your web browser
    2. Click on the "Click Me!" button
    3. A new tab will open, and the original tab will be printing the number. That number is the `window.length` property of the just-opened window.
    4. Navigate the opened window to about:config, and then press back
    5. The number will be 0 despite the window containing 2 iframes.

Expected Results:
The number when navigating to about:config and going back should be 2.

N.B. This works for just about any property of the window. window.length is notable because it is visible cross-process.

A solution for cross-process window proxies will be necessary for bug 1277066, and will also solve this problem for cross-origin references.

NOTE:
This bug is _not_ aiming to fix this problem for same-origin properties, rather it aims to make cross-origin navigations maintain a window proxy reference, and treat all windows which are reached through such a process as cross-origin. This means it will only support cross-origin properties like window.length.

Comment 1

[Samael Wang [:freesamael] (away for now)]

Just an interesting note, this sounds exactly what chromium does for site isolation project recently.

http://www.chromium.org/developers/design-documents/site-isolation#TOC-Project-Tasks

> Cross-Process JavaScript
> ...
> We support all required interactions, including frame placeholders, postMessage, close, closed, 
> focus, blur, and assignments to window.location between top-level windows in different processes.

Comment 2

[Nika Layzell [:nika] (ni? for response)]

That is very similar to what we would want to do for this bug. It might be interesting to look at what chrome is doing for that.

Comment 3

[Nika Layzell [:nika] (ni? for response)]

I might not be working on this for a while. Unassigning myself.

Comment 4

[Anne (:annevk)]

This bug still seems valid, but at this point I think it mainly boils down to history.length being wrong and not the Window object in general being problematic.