1936647 - Improve font fingerprinting detection

Status: ASSIGNED

(Core :: Privacy: Anti-Tracking, enhancement)

Description

[Fatih Kilic [:fkilic]]

Currently, our font fingerprinting detection works by detecting when there's more than 60 cache misses. This is a good method, but due to many properties of fonts (see code block 1) cache misses happen very frequently. On top of that, generic fonts, such as sans-serif, monospace etc. count towards this number as well. On rich pages with many different sized fonts, weights, icons etc. we may get false positives. This bug aims to fix this issue by checking only font family names

Code block 1:

style, weight, stretch, size, sizeAdjust, family, kerning, opticalSizing, synthesisWeight, synthesisStyle, synthesisSmallCaps, synthesisPosition, fontFeatureSettings, fontVariationSettings, languageOverride, variantAlternates, variantCaps, variantEastAsian, variantLigatures, variantNumeric, variantPosition, variantWidth, variantEmoji

Comment 1

[Fatih Kilic [:fkilic]]

Attachment: Bug 1936647: Improve font fingerprinting detection. r?tjr

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/de74f9fffac1
Improve font fingerprinting detection. r=tjr

Comment 3

[Atila Butkovits]

Backed out for causing failures at PLDHashTable.h.

Backout link: https://hg.mozilla.org/integration/autoland/rev/7f5fd9b4d3452ee1132204bda40042e760dfeef4

Push with failures: https://treeherder.mozilla.org/jobs?repo=autoland&resultStatus=testfailed%2Cbusted%2Cexception%2Cretry%2Cusercancel&revision=de74f9fffac1ddbc302a965cf2f4d0473c25bace&selectedTaskRun=ChLC7Y5URUuIBmE6CpXpUQ.0

Failure log: https://treeherder.mozilla.org/logviewer?job_id=494440956&repo=autoland&lineNumber=10724

Comment 4

[Fatih Kilic [:fkilic]]

Thank you I'll take a look into it.