when user starts a new sync chain the modal needs to prevent cancelation

[cezaraugusto]

Test plan

See brave/brave-core#1193

Description

1. Clear profile
2. Click "start a new sync chain"
3. Click "tablet or phone"
4. Try to cancel the modal
5. A new modal appears asking if you are sure about closing it

[LaurenWags]

@cezaraugusto does this refer to the following scenario:
Start sync chain on device A
Enter code words on device B
Device B "completes" joining the sync chain (meaning, the screen where words were entered closes automatically to show the page which lists devices).
Device A still hasn't completed (recognized the chain has been created?) and the screen showing the words is still displayed.
User thinks they have to close this window manually on Device A, so they do and now the chain is seemingly lost?

....asking because I just did this.

[cezaraugusto]

hey @LaurenWags yes, correct. Added QA/no label as it shouldn't change the current flow but will change the application logic.

[cezaraugusto]

moving to 0.59 per last sync meeting

[rossmoody]

The most up to date design spec for Sync can be found right here.

[cezaraugusto]

changing to QA/yes as it has valid steps to check the new feature

[srirambv]

Verification passed on

Brave	0.59.20 Chromium: 72.0.3626.28 (Official Build) beta(64-bit)
Revision	997b1040b63bac324e815797ba52be0cd8f616ed-refs/branch-heads/3626@{#461}
OS	Linux

Verification passed on

Brave	0.59.20 Chromium: 72.0.3626.28 (Official Build) beta (64-bit)
Revision	997b1040b63bac324e815797ba52be0cd8f616ed-refs/branch-heads/3626@{#461}
OS	Windows 10

Verified passed with

Brave	0.59.20 Chromium: 72.0.3626.28 (Official Build) beta(64-bit)
Revision	997b1040b63bac324e815797ba52be0cd8f616ed-refs/branch-heads/3626@{#461}
OS	Mac OS X

• Verified test plan for this issue in fix multiple sync issues brave-core#1193