WebRTC block sometimes not working on private tabs running tor

[srirambv]

Test Plan

1. Clean install 0.23.17
2. Open a Tor tab and visit https://diafygi.github.io/webrtc-ips/, ensure no ip is listed
3. Disable shields on the same Tor tab, still no ip's are listed
4. Open a Private tab and visit https://diafygi.github.io/webrtc-ips/ , ensure local ip is shown
5. Enable Block all fingerprint, no ip should be shown on Private tab

Description

WebRTC not working on private tabs running tor

Steps to Reproduce

1. Clean install 0.23.7
2. Open a private tab and visit https://diafygi.github.io/webrtc-ips/, no local ip address is shown
3. Disable shields, still no local ip address shown
4. Open a new private tab, disable Tor
5. Visit https://diafygi.github.io/webrtc-ips/ in the same tab from step 4, local ip address is shown
6. Enable Block all fingerprint, local ip not shown
7. Open a 3rd private tab and enable Tor
8. Visit https://diafygi.github.io/webrtc-ips/ in 3rd private tab
9. Open shields, block all fingerprint is enabled which should not show local ip address but still shows the local IP

Actual result:
WebRTC block not working on private tabs running tor

Expected result:
Should work correctly

Reproduces how often:
100%

Brave Version

about:brave info:

Brave	0.23.7
V8	6.6.346.32
rev	f0e0dea
Muon	6.1.5
OS Release	10.0.16299
Update Channel	Developer
OS Architecture	x64
OS Platform	Microsoft Windows
Node.js	7.9.0
Brave Sync	v1.4.2
libchromiumcontent	66.0.3359.181

Reproducible on current live release:
N/A

Additional Information

[diracdeltas]

repro'ed this using simpler steps:

1. go to https://diafygi.github.io/webrtc-ips/ in tor private tab
2. disable shields
3. webrtc still blocked
4. open new tor tab, go to https://diafygi.github.io/webrtc-ips/ again
5. webrtc not blocked this time

[diracdeltas]

currently blocked on brave/muon#602

[jumde]

Fixed by: #14402

Commit: 051109c

[srirambv]

Verified on Windows 10 x64 using

• 0.23.16 - 2042c45
• Muon - 7.1.1
• libchromiumcontent - 67.0.3396.87

Verified with macOS 10.12.6 using

• 0.23.17 bc754eb
• Muon 7.1.2
• libchromiumcontent 67.0.3396.87

Verified on Ubuntu 18.04 x64 using the following build:

• 0.23.17 bc754eb
• muon: 7.1.2
• libchromiumcontent: 67.0.3396.87