sergz Reporter
	Description • 8 years ago

User Agent: Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/48.0.2564.116 Safari/537.36

Steps to reproduce:

To reproduce the bug one can try the following code in the Browser console:

let browser = window.getBrowser();
let tab = browser.addTab("about:blank");
console.log(tab.linkedBrowser.outerWindowID);
setTimeout(function(){console.log(tab.linkedBrowser.outerWindowID);}, 20);

JIC, in my extension the code is executed in chrome process and `window` is `Services.wm.getMostRecentWindow("navigator:browser");`.


Actual results:

Actual results:
In e10s `tab.linkedBrowser.outerWindowID` is firstly `null` however after some delay (~20msec on my machine) it is initialized to the actual number (e.g. 2147483652).
In FF 45 `tab.linkedBrowser.outerWindowID` is always already initialized to some number.



Expected results:

Expected results:
`tab.linkedBrowser.outerWindowID` should be already initialized to the actual number after the returning from `browser.addTab("about:blank")`.


Generally speaking it may be not an issue that it is initialized in a background however what is the reliable way to be notified when it's ready in that case?

	Mike Conley (:mconley) (:⚙️)
	Comment 1 • 8 years ago

Hey sergz,

When the remote browser is loaded, it sends a sync "Browser:Init" message up to the parent to inform the parent of the outerWindowId.

In the future, we might want to add some code to browser.xml / remote-browser.xml that returns a Promise that resolves when the outerWindowId is available, but for now, you can maybe work around this by listening for the Browser:Init message on the browser that has opened.

	Andrew Overholt [:overholt]
	Comment 2 • 8 years ago

Mike, I'm marking this as "backlog" but if you think it'll be fixed in the new few months, feel free to mark it as "fixlater" or even "fixnow".

	sergz Reporter
	Comment 3 • 8 years ago

(In reply to Mike Conley (:mconley) - (needinfo me!) from comment #1)
> When the remote browser is loaded, it sends a sync "Browser:Init" message up
> to the parent to inform the parent of the outerWindowId.
That works good, thanks a lot.

	Firefox Bug Husbandry Bot
	Comment 4 • 7 years ago

With Firefox 57 only WebExtensions are permitted and are, by default, e10s compatible.