Levels of protection update proposal

[Švancár Matúš]

Hi everyone,

porting of Brave's fingerprinting protection is finished and there 
aren't compatibility issues as far as I know. So far testing revealed 
that ported countermeasures are working as intended.
Therefore I think we should change protection levels as follows:

Level 2: Change all covered APIs to randomizing approach based on 
session/domain keys, thus - Canvas methods will return slightly modified 
image data, methods isPointInPath and isPointInStroke will return false 
with ~5% probability, Web Audio methods will return slightly modified 
audio data, WebGL methods will mask vendor and renderer, alter whole 
number return values in some functions and return modified image data 
from readPixels, deviceMemory and hardwareConcurrency values will be 
randomized (but valid), enumerateDevices will return shuffled list with 
additional 0-4 fake devices, navigator.plugins will return shuffled list 
with additional 2 fake plugins. Rest of options should remain the same 
as current level 2.

Level 3: Canvas methods isPointInPath and isPointInStroke will always 
return false. Rest should be fine as it is.

This is just a summary, you can see which methods/functions are affected 
in specific wrappers. There may be things needing changes but generally 
tests have so far shown that proposed Level 2  breaks less sites than 
current level 2 while providing better protection. Hit me up if you have 
any comments/suggestions or I didn't explain something clearly enough.

Thanks for feedback,
Matúš Švancár