1762851 - Page is unresponsive and images don't load on carousell.sg with ETP - Strict enabled

Status: VERIFIED FIXED

(Core :: Privacy: Anti-Tracking, defect, P3)

Description

[Oana Arbuzov [:oanaarbuzov]]

Attachment: StrictVsStandard.png

Environment:
Browser / Version: Firefox Nightly 100.0a1 (2022-04-03)
Operating System: Windows 10 Pro

Steps to Reproduce:

1. Navigate https://www.carousell.sg/search/ps3
2. Observe the page.

Expected Behavior:
Content loads correctly and the page is responsive.

Actual Behavior:
The page is unresponsive and images don't load.

Note:

1. With ETP - Standard.
2. Screenshot attached.

Comment 1

[Thomas Wisniewski [:twisniewski]]

I even get a slow-script warning, and can't open the debugger to find out what's happening. But if I disable the SmartBlock shim for Google Publisher Tags, it seems to work, so it would appear that the site is somehow tripping that shim into an infinite loop (or something like that). I'll investigate ASAP.

Comment 2

[Thomas Wisniewski [:twisniewski]]

So there are two things to do here. First, the page is catastrophically failing to deal with the case where Google PubAds tells it that an ad slot is empty, which the shim is doing. So we will need to pretend it's not empty.

Also, the page will end up having a loading animation for the ad-slot, which will make it appear like some of the grid-items on their page aren't loading properly if we don't also clear the loading animation. Thankfully it looks like PubTags is meant to clear the element in question (it's the ad-slot) as it "renders" the ad, so it should be safe for us to do so as well. This will end up leaving an empty spot in their grid, but that's better than the loading animation implying that an expected item is failing to load.

I have a candidate patch almost ready which should do the trick.

Comment 3

[Thomas Wisniewski [:twisniewski]]

Attachment: Bug 1762851 - Have the SmartBlock Google Publisher Tags shim report non-empty slots and clear them as sites expect; r?denschub

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/a728b8535455
Have the SmartBlock Google Publisher Tags shim report non-empty slots and clear them as sites expect; r=webcompat-reviewers,ksenia

Comment 5

[Iulian Moraru]

https://hg.mozilla.org/mozilla-central/rev/a728b8535455

Comment 6

[Hani Yacoub, Desktop QA]

Verified as fixed on macOS 11.6, Windows 10 x64 and on Ubuntu 20.04 x64 on Firefox 102.0b3 and Nightly 103.0a1.