This happened during one of my meetings where I was collaborating in a google doc, then switched tabs to review some perf regressions and review pushlogs. After coming back to the google docs tab, I was unable to type anywhere in the gdoc. Browsing the doc was working fine.

Browser console showed this error when I tried to click anywhere to type:
TypeError: can't access property "originAttributes", this.browser.contentPrincipal is nullSessionStore.jsm:1013:11
notifySHistoryChanges resource:///modules/sessionstore/SessionStore.jsm:1013
OnHistoryReplaceEntry resource:///modules/sessionstore/SessionStore.jsm:1045

Reloading the page fixed it. I don't have better STR for a reliable repro. P.S. I was running with Fission.

smaug said this could be a focus issue.

According to Neha, the page up and page down keys work and the text insertion point shows up. This suggests that this is something other than focus.

Since I was able to go up and down the doc, Henri said it's unlikely that it's a focus issue..

I was able to reproduce it with the following steps:

1. Enable Fission
2. In a window, open a new google doc and verify that you are able to type.
3. In another window, open google calendar and create a meeting for yourself with a notification reminder. I created a meeting starting in 2 minutes with notification 1 minute before.
4. Now wait in the google docs window.
5. When the google calendar window pops up the meeting notification, try typing in the google doc without interacting with the calendar window. This failed for me.
6. Click on OK for the meeting notification and now the typed buffer will appear in the doc. And further typing will work.

Interestingly, I was still able to scroll up and down the doc but not type. Henri, ideas?

I'll test this without Fission too.

Tried this without Fission and was able to reproduce the behavior.

1. If google calendar and google doc are not in the same process in the two separate windows, then I'm able to type in the doc when the other window has the meeting notification.
2. If I ensure that those two are sharing process (as PIDs are cycled), then the same behavior as Fission is seen. For non-Fission, it doesn't even have to be the same origin so you could load google calendar in one, and youtube in the other.

ok, this is then bug 1662265

Er, maybe not, since bug 1662265 landed after this was filed.

Or perhaps this bug was first about something else and now about regression from bug 1662265.

Does Chrome not show an alert in the other tab?

I'm no longer able to reproduce this so Olli's idea of dom.input_events.canSuspendInBCG.enabled being the cause seems correct. This got disabled in bug 1685577 so this bug is no longer a problem for Fission.