Choose Device Type modal is not shown after going offline and back online

[btlechowski]

Found when testing new sync UI changes #6941.

Steps to Reproduce

1. Open brave://sync
2. Go offline
3. Click Start a new Sync Chain
4. Wait a minute
5. Go online
6. Wait till Choose Device Type modal is shown

IMPORTANT: after page reload, the modal is shown

Actual result:

Choose Device Type modal is not shown
The UI is stuck on sync creation

Expected result:

Choose Device Type modal is shown

Reproduces how often:

100% repro rate

Brave version (brave://version info)

Brave	1.5.46 Chromium: 79.0.3945.130 (Official Build) nightly (64-bit)
Revision	e22de67c28798d98833a7137c0e22876237fc40a-refs/branch-heads/3945@{#1047}
OS	Ubuntu 18.04 LTS

cc @brave/legacy_qa @rebron @cezaraugusto @AlexeyBarabash @jsecretan

[cezaraugusto]

@AlexeyBarabash do you think we can intercept offline requests in the back-end? Doing this with JavaScript is not reliable since there's no native listener in WebAPIs for offline events.

[AlexeyBarabash]

@cezaraugusto I agree, doing this with javascript in UI is not an option.
I think we have the error event for such case but I need to check why it isn't passed to UI.

[AlexeyBarabash]

This is not applicable now, because with Sync v2 when we press Start a new Sync Chain - then the passphase is generated but there is no any communication with the server, so offline/online doesn't have any effect on this.

And even I would do:

1. go offline
2. create sync chain
3. go online

• then the chain gets created.

So I am closing this issue.