1491051 - document_start scripts are running one tick later since the patch for bug 1437861

Status: RESOLVED FIXED

(WebExtensions :: General, enhancement, P1)

Description

[Rob Wu [:robwu]]

The content script injection logic is carefully designed to avoid awaiting microtasks (promises) when a document_start is being executed.

In this change, an unnecessary await was introduced:
https://hg.mozilla.org/mozilla-central/rev/f151c2fa525f#l1.12

In tests where content scripts run once, this does not result in an observable difference because the first script is not preloaded so we already have an await + wait for promise.

This problem becomes visible when a page is loaded again while a script is cached, because there is no document.blockParsing call.

Comment 1

[Luca Greco [:rpl] [:luca] [:lgreco]]

Attachment: Bug 1491051 - Avoid awaiting a promise when all the content scripts are already precompiled and cached. r?mixedpuppy!,robwu

Comment 2

[Rob Wu [:robwu]]

Comment on attachment 9008827 [details]
Bug 1491051 - Avoid awaiting a promise when all the content scripts are already precompiled and cached. r?mixedpuppy!,robwu

Rob Wu [:robwu] has approved the revision.

Comment 3

[Shane Caraveo (:mixedpuppy)]

Comment on attachment 9008827 [details]
Bug 1491051 - Avoid awaiting a promise when all the content scripts are already precompiled and cached. r?mixedpuppy!,robwu

Shane Caraveo (:mixedpuppy) has approved the revision.

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/5d78ab715d4f
Avoid awaiting a promise when all the content scripts are already precompiled and cached. r=robwu,mixedpuppy

Comment 5

[Noemi Erli[:noemi_erli]]

https://hg.mozilla.org/mozilla-central/rev/5d78ab715d4f

Comment 6

[Victor Carciu]

Can you please add some STRs(and a test webextesnsion if possible) or mark this issue as "qe-verify-" ?

Comment 7

[Luca Greco [:rpl] [:luca] [:lgreco]]

I'm marking this as qe-verify-, as it is tested in the automated tests added by the same patch that introduced the fix (and it is not an easy one to verify with manual testing).