Remove Background Sync content setting options

[srirambv]

Description

Background Sync should be removed from Content settings page

Steps to Reproduce

1. Settings -> Content Settings -> Background Sync which requires account login

Actual result:

cc: @bridiver @diracdeltas

[bbondy]

I think we'll just remove this option completely? Thoughts @AlexeyBarabash ?

[AlexeyBarabash]

@bbondy @srirambv
I thought this option is for the synchronization of bookmarks/history/setting between devices, which will be replaced with Brave Sync #29 . Then I would vote to remove it.
But if we go there chrome://settings/content/backgroundSync , we will see

which is other thing.
So, I think to keep it, and maybe to rename it to Background sync of recently closed sites data .

I was not aware of this option, but it seems useful. If a page has logout button, which works through async JavaScript without re-load of the page, then when user presses logout and immediately closes the tab potentially he would not be logged out in fact. But this option Allow recently closed sites to finish sending and receiving data (recommended) should allow to complete the operation.

The Chrome native sync for bookmarks/history/etc is not currently shown in Brave-core. Two things are required to see that at least:

1. to re-build with Google API keys with enabled Google Accounts sync;
2. to login in browser with Google Account.

About this issue: either to keep it as and close, or rename the item. I would just close.

[bbondy]

Just going to remove it

[GeetaSarvadnya]

Verification Passed on:

Brave	0.55.5 Chromium: 70.0.3538.16 (Official Build) dev (64-bit)
Revision	16ed95b41bb05e565b11fb66ac33c660b721f778-refs/branch-heads/3538@{#306}
OS	Windows

Verification Passed on

Brave	0.55.5 Chromium: 70.0.3538.16 (Official Build) dev (64-bit)
Revision	16ed95b41bb05e565b11fb66ac33c660b721f778-refs/branch-heads/3538@{#306}
OS	Linux

Went through verification using the following build under macOS 10.13.6 x64 - PASSED

Brave	0.55.6 Chromium: 70.0.3538.16 (Official Build) dev (64-bit)
Revision	16ed95b41bb05e565b11fb66ac33c660b721f778-refs/branch-heads/3538@{#306}
OS	Mac OS X