previously visited websites being added into table after enabling rewards

[kjozwiak]

Test Plan

brave/brave-core#488

Original Report

Description

When enabling chrome://rewards, you'll notice that the auto-contribute table is being populated by previously visited websites. This could lead to several privacy issues. Websites that have been visited after enabling rewards should be the only ones appearing in the table.

Example: I visited several personal/sketchy websites and didn't use PB/Incognito. I enable rewards and notice that these websites are now being listed in the table as well.

Steps to Reproduce

1. launch 0.55.5 Chromium: 70.0.3538.16 and visit ~5 websites
2. enable rewards via chrome://rewards
3. wait ~1min and you'll notice the table will be populated with those websites

Actual result:

Expected result:

Websites/Publishers/Channels that have been previously visited shouldn't be populated into the auto-contribute table once chrome://rewards is enabled.

Reproduces how often:

100% reproducible using the above STR.

Brave version (chrome://version info)

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

Reproducible on current release:

Yes, currently reproducible under 0.55.5 Chromium: 70.0.3538.16 which is the current live build.

[NejcZdovc]

this should be fixed by brave/brave-core#419

[LaurenWags]

Verified passed with

Brave	0.55.10 Chromium: 70.0.3538.22 (Official Build) beta(64-bit)
Revision	ac9418ba9c3bd7f6baaffa0b055dfe147e0f8364-refs/branch-heads/3538@{#468}
OS	Mac OS X

Used test plan from brave/brave-core#488

Verification passed on

Brave	0.55.11 Chromium: 70.0.3538.35 (Official Build) beta (64-bit)
Revision	28dcb499844fa40c28d5f62e337876cb936f79f5-refs/branch-heads/3538@{#678}
OS	Windows 7

Used test plan from brave/brave-core#488

Verification Passed on

Brave	0.55.11 Chromium: 70.0.3538.35 (Official Build) beta (64-bit)
Revision	28dcb499844fa40c28d5f62e337876cb936f79f5-refs/branch-heads/3538@{#678}
OS	Linux