pre-roll ads on twitch not always blocked

[LaurenWags]

Description

Sometimes pre-roll ads on twitch are not blocked.

Steps to Reproduce

1. Navigate to twitch
2. Watch some live streams and VODs

Actual result:

Ads are not always blocked. Seems to happen more with live streams than VODs.

Expected result:

Pre-roll ads should be blocked.

Reproduces how often:

intermittent

Brave version (chrome://version info)

Brave	0.55.12 Chromium: 70.0.3538.45 (Official Build) beta(64-bit)
Revision	cbdc32e4334458954e9def214d7e5fa1ca1960eb-refs/branch-heads/3538@{#830}
OS	Mac OS X

Reproducible on current release:

• Does it reproduce on brave-browser dev/beta builds? yes (intermittent)
• Does it reproduce on browser-laptop? yes (intermittent)

Website problems only:

• Does the issue resolve itself when disabling Brave Shields? n/a
• Is the issue reproducible on the latest version of Chrome? n/a

Additional Information

This also happened sometimes on browser-laptop.
cc @brave/legacy_qa for verification on other platforms

[lukemulks]

+1
Able to repro on win10x64

Brave is up to date
Version 0.59.35 Chromium: 72.0.3626.81 (Official Build) (64-bit)

seems like a regression from the fix shipped in this update https://github.com/brave/browser-laptop/releases/tag/v0.23.31dev but requires additional investigation.

observed here:
https://www.twitch.tv/loltyler1

Request URL: https://usher.ttvnw.net/api/channel/hls/chess.m3u8?allow_source=true&baking_bread=true&baking_brownies=true&baking_brownies_timeout=1050&fast_bread=true&p=8927097&player_backend=mediaplayer&playlist_include_framerate=true&reassignments_supported=true&rtqos=control&sig=f2f84f2526c8c3db50e62734bca3bc8498eecd97&token=%7B%22adblock%22%3Atrue%2C%22authorization%22%3A%7B%22forbidden%22%3Afalse%2C%22reason%22%3A%22%22%7D%2C%22blackout_enabled%22%3Afalse%2C%22channel%22%3A%22chess%22%2C%22channel_id%22%3A7601562%2C%22chansub%22%3A%7B%22restricted_bitrates%22%3A%5B%5D%2C%22view_until%22%3A1924905600%7D%2C%22ci_gb%22%3Afalse%2C%22geoblock_reason%22%3A%22%22%2C%22device_id%22%3A%22b51c477dcf960d05%22%2C%22expires%22%3A1549571562%2C%22game%22%3A%22Chess%22%2C%22hide_ads%22%3Afalse%2C%22https_required%22%3Atrue%2C%22mature%22%3Afalse%2C%22partner%22%3Afalse%2C%22platform%22%3A%22web%22%2C%22player_type%22%3A%22frontpage%22%2C%22private%22%3A%7B%22allowed_to_view%22%3Atrue%7D%2C%22privileged%22%3Afalse%2C%22server_ads%22%3Atrue%2C%22show_ads%22%3Atrue%2C%22subscriber%22%3Afalse%2C%22turbo%22%3Afalse%2C%22user_id%22%3Anull%2C%22user_ip%22%3A%2273.252.157.21%22%2C%22version%22%3A2%7D&cdm=wv

Observing ad block detection, user IP and device ID passing in the video request ^

adblock%22%3Atrue
user_ip%22%3A%2273.252.157.21
device_id%22%3A%22b51c477dcf960d05

config appears to use wasm and webworkers, but again, needs more investigation.

cc: @jonathansampson as FYI

[Brave-Matt]

+1 (/a few) from Reddit:
https://www.reddit.com/r/brave_browser/comments/b0a9xw/why_am_i_seeing_ads_on_twitch/

[LaurenWags]

Still occurs with below build

Brave | 1.19.75 Chromium: 87.0.4280.101 (Official Build) dev (x86_64)
-- | --
Revision | 9407c80213cda69c2b7abcb4fa8e3f74488f4956-refs/branch-heads/4280@{#1807}
OS | macOS Version 10.15.7 (Build 19H15)