Enable Web Serial by default

[ShivanKaul]

Description

We currently disable Web Serial by default, and allow enabling via flag. On looking at the user flow now, I don't see a reason to keep this disabled. Users get a permission popup and the API doesn't increase fingerprinting surface by default. Mozilla also changed their position recently; in Chromium Web Serial use requires a permission popup.

Steps to reproduce

Check status of brave://flags/#brave-web-serial-api

Actual result

Is off by default

Expected result

Should be on by default

Reproduces how often

Easily reproduced

Brave version (brave://version info)

1.68.40 Chromium: 125.0.6422.76 (Official Build) nightly (arm64) (I'm on Nightly but this is on all versions)

Channel information

• release (stable)
• beta
• nightly

Reproducibility

• with Brave Shields disabled
• with Brave Rewards disabled
• in the latest version of Chrome

Miscellaneous information

No response

[mkarolin]

Test plan:

1. Start Brave and navigate to permissions.site
2. Click on Serial button

Observe:
Permission prompt shows up.

3. Cancel from the permission prompt
4. Navigate to brave://settings/content
5. Click Additional permissions
6. Verify that Serial ports is listed

[mkarolin]

Note on deviation from the original description. Instead of making the flag enabled by default, the flag was removed entirely.

[stephendonner]

Verified PASSED using

Brave | 1.69.53 Chromium: 127.0.6533.17 (Official Build) nightly (x86_64)
-- | --
Revision | bedcc2e74ce45bd641d2946e0d870d68ba08b8e9
OS | macOS Version 11.7.10 (Build 20G1427)

Steps:

1. installed 1.69.53
2. launched Brave
3. opened brave://flags
4. searched for serial
5. confirmed no matching flags
6. loaded permission.site
7. clicked on Serial
8. confirmed permissions prompt
9. clicked on Connect for the first highlighted entry
10. confirmed the Serial button on the page turned green (enabled)
11. clicked again on Serial

Confirmed Web Serial was enabled by default, has no flag, and I could successfully pair

example	example	example	example

[MadhaviSeelam]

Verification PASSED using

Brave | 1.69.122 Chromium: 127.0.6533.57 (Official Build) beta (64-bit)
-- | --
Revision | bd77e9b76a8e67ff2bf9f62f1df7d60378ca811f
OS | Windows 11 Version 23H2 (Build 22631.3880)

Case 1: New install - PASSED

1. installed 1.69.122
2. launched Brave
3. opened brave://flags and searched for #brave-web-serial-api
4. confirmed No matching experiments message shown
5. loaded permission.site
6. clicked on Serial
7. confirmed permissions prompt
8. clicked on Connect for the first highlighted entry
9. confirmed the Serial button on the page turned green (enabled)
10. clicked again on Serial to confirm the device is paired
11. cancel from the permission prompt
12. navigated to brave://settings/content
13. clicked Additional permissions
14. confirmed Serials ports entry is shown
15. opened Serial ports page
16. confirmed pages shows the entry for the site https://permissions.site/

step 3	step 7	step 8	step 9	step 10	step 13	step 14	step 16

Case 2: Reset Permissions - PASSED

1. Continue from Case 1
2. clicked the tune icon in the URL bar
3. clicked Reset Permission button
4. navigated brave://settings/content and clicked Additional permissions
5. clicked Serial ports
6. confirmed no entry is shown in the No serial ports found

step 3a	step 3b	step 5	step 6

Case 3: Upgrade - PASSED

1. installed 1.68.128
2. launched Brave
3. opened brave://flags and searched for #brave-web-serial-api
4. confirmed Web Serial API flag is disabled by default
5. opened brave://settings/content
6. confirmed Serial ports entry is not listed in Additional permissions
7. closed Brave
8. renamed Brave profile to Brave-Manager-Beta
9. installed 1.69.122
10. relaunched Brave
11. opened brave://flags and searched for #brave-web-serial-api
12. confirmed No matching experiments message shown
13. loaded https://permission.site
14. clicked on Serial
15. confirmed permissions prompt
16. clicked on Connect for the first highlighted entry
17. confirmed the Serial button on the page turned green (enabled)
18. clicked again Serial button to confirm the device is paired
19. navigated to brave://settings/content
20. clicked Additional permissions
21. confirmed Serials ports entry is shown
22. opened Serial ports page
23. confirmed pages shows the entry for the site https://permission.site/

step 4	step 6	step 12	step 16-17	step 18	step 21	step 23

[MadhaviSeelam]

Verification PASSED using

Brave | 1.69.124 Chromium: 127.0.6533.73 (Official Build) beta (arm64)
-- | --
Revision | dbc9035349f74e493f3293d93f4cbf35c597dfec
OS | macOS Version 13.5 (Build 22G74)

Case 1: New install - PASSED

1. installed 1.69.124
2. launched Brave
3. opened brave://flags and searched for #brave-web-serial-api
4. confirmed No matching experiments message shown
5. loaded permission.site
6. clicked on Serial
7. clicked Allow
8. confirmed permissions prompt shown
9. clicked on Connect for the first highlighted entry
10. confirmed the Serial button on the page turned green (enabled)
11. clicked again on Serial to confirm the device is paired
12. cancel from the permission prompt
13. navigated to brave://settings/content
14. clicked Additional permissions
15. confirmed Serials ports entry is shown
16. opened Serial ports page
17. confirmed page shows the entry for the site https://permissions.site/

step 4	step 7	step 8-9	step 10-11	step 13 -15	step 17

Case 2: Reset Permissions - PASSED

1. Continue from Case 1
2. clicked the tune icon in the URL bar for the permission.site
3. clicked Reset Permission button
4. navigated brave://settings/content and clicked Additional permissions
5. clicked Serial ports
6. confirmed no entry is shown in the No serial ports found

step 3a	step 3b	step 5	step 6

Case 3: Upgrade - PASSED

1. installed 1.68.128
2. launched Brave
3. opened brave://flags and searched for #brave-web-serial-api
4. confirmed Web Serial API flag is disabled by default
5. opened brave://settings/content
6. confirmed Serial ports entry is not listed in Additional permissions
7. closed Brave
8. renamed Brave profile to Brave-Manager-Beta
9. installed 1.69.122
10. relaunched Brave
11. opened brave://flags and searched for #brave-web-serial-api
12. confirmed No matching experiments message shown
13. loaded https://permission.site
14. clicked on Serial
15. confirmed permissions prompt shown
16. clicked on Connect for the first highlighted entry
17. confirmed the Serial button on the page turned green (enabled)
18. clicked again Serial button to confirm the device is paired
19. cancel from the permission prompt
20. navigated to brave://settings/content
21. clicked Additional permissions
22. confirmed Serials ports entry is shown
23. opened Serial ports page
24. confirmed pages shows the entry for the site https://permission.site/

step 4	step 6	step 12	step 15-17	step 18	step 20-22	step 24

[MadhaviSeelam]

Verification PASSED using

Brave	1.69.128 Chromium: 127.0.6533.73 (Official Build) beta (64-bit) 
Revision	715445841b1da480bcc24c12077a6dc926951996
OS	Linux

Case 1: New install - PASSED

1. installed 1.69.124
2. launched Brave
3. opened brave://flags and searched for #brave-web-serial-api
4. confirmed No matching experiments message shown
5. loaded permission.site
6. clicked on Serial
7. confirmed permissions prompt shown
8. clicked on Connect for the first highlighted entry
9. confirmed the Serial button on the page turned green (enabled)
10. clicked again on Serial to confirm the device is paired
11. cancel from the permission prompt
12. navigated to brave://settings/content
13. clicked Additional permissions
14. confirmed Serials ports entry is shown
15. opened Serial ports page
16. confirmed page shows the entry for the site https://permissions.site/

step 4	step 7-8	step 9-10	step 12 -14	step 16

Case 2: Reset Permissions - PASSED

1. Continue from Case 1
2. clicked the tune icon in the URL bar for the permission.site
3. clicked Reset Permission button
4. clicked Reload button
5. navigated brave://settings/content and clicked Additional permissions
6. clicked Serial ports
7. confirmed no entry is shown in the No serial ports found

step 3a	step 3b	step 4	step 5	step 6

Case 3: Upgrade - PASSED

1. installed 1.68.128
2. launched Brave
3. opened brave://flags and searched for #brave-web-serial-api
4. confirmed Web Serial API flag is disabled by default
5. opened brave://settings/content
6. confirmed Serial ports entry is not listed in Additional permissions
7. closed Brave
8. renamed Brave profile to Brave-Manager-Beta
9. installed 1.69.128
10. relaunched Brave
11. opened brave://flags and searched for #brave-web-serial-api
12. confirmed No matching experiments message shown
13. loaded https://permission.site
14. clicked on Serial
15. confirmed permissions prompt shown
16. clicked on Connect for the first highlighted entry
17. confirmed the Serial button on the page turned green (enabled)
18. clicked again Serial button to confirm the device is paired
19. cancel from the permission prompt
20. navigated to brave://settings/content
21. clicked Additional permissions
22. confirmed Serials ports entry is shown
23. opened Serial ports page
24. confirmed pages shows the entry for the site https://permission.site/

step 4	step 6	step 13	step 15-17	step 18-19	step 21-22	step 25

[Dinth]

Many thanks! Sorry for throwing my couple of pence here, but this is a great decision! Im not a dev, but i am an IT Security expert who done fair bit of threat modelling and risk assessments, and i have never seen the point of removing that feature from the browser.

Mozilla also mozilla/standards-positions#720 (comment);

Looking at what Mozilla does is not the best thing, their market share is constantly getting smaller and not without a reason. Not implementing WebSerial in FF was one of those reasons.