1465828 - Navigations in discarded tabs via tabs.update are undone when that tab is activated again

Status: RESOLVED DUPLICATE of bug 1583281

(WebExtensions :: Android, defect, P3)

Description

[Rob Wu [:robwu]]

I attached the WebIDE debugger (F8) to a Firefox Beta for Android instance (Firefox 61, buildID 20180514150347), inspected the main process and switched the context to an extension (with the tabs permission so I can see the URL, e.g. uBlock).

In the browser all tabs except for the last one were zombified/"discarded" (I guess that you can trigger this by causing memory pressure, e.g. by opening another app that uses lots of memory).

browser.tabs.query({
  discarded: true,
}).then(tabs => console.log(tabs[0].id));

Then I triggered a navigation, e.g.

browser.tabs.update(4, {
  url: 'https://example.com',
});

I can see that the tab has navigated.
However, when I query the tab info, then the tab is still in the "discarded" state:

browser.tabs.get(4).then(console.log);
// { ... discarded: true ..., url: "https://example.com/" ...}

When I switch to the tab, the original URL is restored.


What I expected is:
- After navigating by tabs.update, tab.discarded should be false.
- After tapping on the navigated tab, the tab should not be "restored", but stay at the changed location.



The implementation of tabs.update calls nativeTab.browser.loadURI :
https://searchfox.org/mozilla-central/rev/83a923ef7a3b95a516f240a6810c20664b1e0ac9/mobile/android/components/extensions/ext-tabs.js#306,318

The zombie restoration logic scattered over:
- https://searchfox.org/mozilla-central/rev/83a923ef7a3b95a516f240a6810c20664b1e0ac9/mobile/android/chrome/content/browser.js#3922-3963
- https://searchfox.org/mozilla-central/rev/83a923ef7a3b95a516f240a6810c20664b1e0ac9/mobile/android/components/SessionStore.js#846-859,1462-1480
  (Search for "pending" (including the quotes or __SS to find relevant code).

It seems that the tab management implementation does not account for navigating a zombified tab.

Comment 1

[Jan Henning [:JanH]]

Conversely, tabs.update() shouldn't be stomping over the session history of a discarded tab, though. In principle, the tab needs to be restored first before we can load a new URL the normal way, although a naive implementation would trigger an additional, unneeded load of the previously loaded URL, which isn't ideal. I wonder what Desktop does here?

Comment 2

[Shane Caraveo (:mixedpuppy)]

It seems that the tab management implementation does not account for navigating a zombified tab.

If the platform doesn't support it, we should just throw an error.

Since this is android, lowering priority.

Comment 3

[BugBot [:suhaib / :marco/ :calixte]]

The severity field for this bug is relatively low, S3. However, the bug has 11 votes.
:robwu, could you consider increasing the bug severity?

For more information, please visit auto_nag documentation.

Comment 4

[BugBot (nomail) [:suhaib / :marco/ :calixte]]

The last needinfo from me was triggered in error by recent activity on the bug. I'm clearing the needinfo since this is a very old bug and I don't know if it's still relevant.

Comment 5

[William Durand [:willdurand]]

Since there is no support for discarded tabs, I am marking this bug as a dup of Bug 1583281.