Sync cannot enable chain sometimes

[AlexeyBarabash]

Description

Steps to Reproduce

1. Prepare clear profiles deviceA and deviceB
2. Launch profile A, create new sync chain, ensure sync code is shown, but don't copy the code. Close deviceA.
3. Launch profile B, create new sync chain, copy sync code, don't close.

Actual result:

4. It is possible to launch profile A, enter sync code and nothing will happen

Expected result:

4 Launch profile A. Profile A will have sync enabled with only one self device. It will either display the list of one device or propose to add another device by show the codephrase

Reproduces how often:

Easily

Brave version (brave://version info)

Brave	0.73.1 Chromium: 78.0.3904.50 (Developer Build) (64-bit)
Revision	2accdc52c79976e264cd2694df6db31d1fccd8e8-refs/branch-heads/3904@{#658}

Version/Channel Information:

• Can you reproduce this issue with the current release? not sure
• Can you reproduce this issue with the beta channel? not sure
• Can you reproduce this issue with the dev channel? Yes
• Can you reproduce this issue with the nightly channel? Yes

Other Additional Information:

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

Miscellaneous Information:

[btlechowski]

Added QA/Blocked as testing is blocked due to #6941

[kjozwiak]

Removing QA/Blocked as both brave/brave-core#4407 & brave/brave-core#4408 have been merged. Once we get a new 1.3.x build that's > 1.3.100, QA should be able to verify this issue.

[btlechowski]

Verification passed on

Brave	1.3.111 Chromium: 80.0.3987.85 (Official Build) (64-bit)
Revision	583b05dfa4ffc657f0f7c5cc13f53aa17c9a5bcf-refs/branch-heads/3987@{#791}
OS	Ubuntu 18.04 LTS

Talked to @AlexeyBarabash, The point of this issue is to use custom profiles for the same device. This can be achieved though flag --user-data-dir=[PATH]
Example:
Profile A: --user-data-dir=/home/bartlomiej/.config/BraveSoftware/TEST/A
Profile B: --user-data-dir=/home/bartlomiej/.config/BraveSoftware/TEST/B

Verified test plan from brave/brave-core#3988 (comment)

Verified - I. Check how works reset with Leave Sync Chain button

Verified - II. Check how works reset over pressing cross near this device

Verified - III. Check how works Reset over pressing cross near opposite device

Verified - IV. Check the original STR from #6504 becomes not applicable

Verified - V. Check this PR build works with from old version by STR at brave-browser#6504
Used Brave Beta at step 4:
/usr/bin/brave-browser-beta --user-data-dir=/home/bartlomiej/.config/BraveSoftware/TEST/A

Verified - VI. Check we send bookmarks as soon as sync is enabled even if there are one device in chain

Verification passed on

Brave	1.3.112 Chromium: 80.0.3987.87 (Official Build) (64-bit)
Revision	449cb163497b70dbf98d389f54e38e85d4c59b43-refs/branch-heads/3987@{#801}
OS	Windows 10 OS Version 1803 (Build 17134.1006)

• Verified the test plan from Sync prefs redo issue 6504 brave-core#3988
  I. Leave sync chain on Device A

Verified with @AlexeyBarabash screen displayed below on Device B is expected when you select any one of the device in below option and click on cancel should take you back to the Sync screen where only Device B is listed


II. Click on Remove this device (x) button on device A

III. Remove Device A from Device B by clicking on Remove (X)

IV. Original STR from #6504 becomes not applicable

V. Verified PR build works with from old version by STR at brave-browser#6504

VI. Verified bookmarks sent as soon as sync is enabled even if there are one device in chain

Verification PASSED on macOS 10.15.3 x64 using the following build:

Brave	1.3.113 Chromium: 80.0.3987.87 (Official Build) (64-bit)
Revision	449cb163497b70dbf98d389f54e38e85d4c59b43-refs/branch-heads/3987@{#801}
OS	macOS Version 10.15.3 (Build 19D76)

I. Check how works reset with Leave Sync Chain button - PASSED

II. Check how works reset over pressing cross near this device - PASSED

III. Check how works Reset over pressing cross near opposite device - PASSED

IV. Check the original STR from #6504 becomes not applicable - PASSED

V. Check this PR build works with from old version by STR at brave-browser#6504 - PASSED

VI. Check we send bookmarks as soon as sync is enabled even if there are one device in chain - PASSED