no error message for bad behavior when unable to connect to sync servers

[LaurenWags]

Description

Follow up to brave/brave-core#1019

The final scenario in the test plan for the above PR did not pass QA. Scenario is Bad behavior from Sync servers in PR.

Steps to Reproduce

1. Create a sync chain and ensure you see two devices
2. Quit Brave
3. Launch Brave without internet
4. You should see a Unable to connect to the Sync servers. error dialog

Actual result:

No error dialog

Expected result:

Should be error dialog

Reproduces how often:

easily

Brave version (brave://version info)

Brave	0.58.12 Chromium: 71.0.3578.80 (Official Build) (64-bit)
Revision	2ac50e7249fbd55e6f517a28131605c9fb9fe897-refs/branch-heads/3578@{#860}
OS	Mac OS X

Reproducible on current release:

• Does it reproduce on brave-browser dev/beta builds?

Website problems only:

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

Additional Information

cc @brave/legacy_qa for verification on other platforms

[GeetaSarvadnya]

Verification passed on

Brave	0.59.13 Chromium: 72.0.3626.28 (Official Build) beta (64-bit)
Revision	997b1040b63bac324e815797ba52be0cd8f616ed-refs/branch-heads/3626@{#461}
OS	Windows

• Verified the STR from description

• Verification passed on

Brave 0.59.13 Chromium: 72.0.3626.28 (Official Build) beta (64-bit)
Revision 997b1040b63bac324e815797ba52be0cd8f616ed-refs/branch-heads/3626@{#461}
OS Linux

• Verified the STR from description
  

Verified passed with

Brave	0.59.14 Chromium: 72.0.3626.28 (Official Build) beta(64-bit)
Revision	997b1040b63bac324e815797ba52be0cd8f616ed-refs/branch-heads/3626@{#461}
OS	Mac OS X

• Verified STR from description and show message about server error when sync is active brave-core#1128