As seen on bug 1287723 we do not always wait for the readyState to be complete before starting to interact with a new chrome window. As result we run into race conditions which can cause failures in attaching our listeners. Similar to new content windows we should make sure to wait for the window to be completely loaded. For firefox-puppeteer we already have a workaround in place which works pretty well: https://dxr.mozilla.org/mozilla-central/source/testing/puppeteer/firefox/firefox_puppeteer/ui/windows.py#151 To fix this bug I would propose a solution in marionette-server, especially in driver.js. From what I can see right now `switchToWindow()` should be the best place for it. Andreas, what do you think? Is that assumption right or would you propose a different location for that check?

As noticed on bug 1287723 the broken load behavior might only happen for erroneous chrome window URLs. It would need some further investigation. Removing ni? request from Andreas for now.

This will be resolved by https://bugzil.la/marionette-window-tracking.