1609324 - [Fission] Weirdness when going back in some cases (temporarily disable bfcache for Fission-enabled tabs)

Status: VERIFIED FIXED

(Core :: DOM: Navigation, defect, P1)

Description

[James Teh [:Jamie]]

Sorry if this is the wrong component. This scenario causes some weird a11y issues, but in trying to debug them, I discovered that this seems to have implications wider than just a11y.

STR:

1. Ensure Fission is enabled.
2. Open this URL:
   data:text/html,<iframe src="https://google.com/notfound">
3. Examine the tab tooltip.
   • Observe: The tab tooltip lists two pids; e.g. (pid 19620) [F 936]
4. Now open about:blank in the same tab.
5. Press alt+leftArrow to go back. Observe that we return to the document from step 2.
6. Examine the tab tooltip.
   • Expected: Two pids as before.
   • Actual: Only one pid is listed; e.g. (pid 19620) [F ]
7. Press control+r to refresh.
8. Examine the tab tooltip.
   • Observe: The tab tooltip lists two pids as expected.

The a11y impact is that on Windows, the OOP iframe document never seems to be told about its parent COM proxy. I haven't tracked down why yet. However, the fact that this causes the pids to show up incorrectly leads me to believe there is a deeper problem here.

Comment 1

[Chris Peterson [:cpeterson]]

Nika says session history is known busted with Fission enabled. kmag says there are no active BrowsingContexts in the parent after browsing back.

We should temporarily disable bfcache for Fission-enabled tabs.

We should remember to test this scenario when we re-enable bfcache with Fission. Can we add a test now?

Tracking for Fission dogfooding (M5)

Comment 2

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

I'll post a patch to disable bfcache for documents with remote subframes

Comment 3

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

Attachment: Bug 1609324 - Disable BFCache when remote subframes are present,

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/a9091629c4f8
Disable BFCache when remote subframes are present, r=smaug

Comment 5

[Oana Pop-Rus]

https://hg.mozilla.org/mozilla-central/rev/a9091629c4f8

Comment 6

[Emil Ghitta, QA [:emilghitta]]

I have managed to reproduce this issue using Firefox 74.0a1 (BuildId:20200114214307).

This issue is verified fixed using Firefox 75.0a1 (BuildId:20200219095352) and Firefox 76.0a1 (BuildId:20200322212426) on Windows 10 64bit, macOS 10.14 and Ubuntu 18.04 64bit.

Tested only on nightly builds (since this requires fission to be enabled).