Ad notifications not being shown after re-enabling until browser is restarted

[LaurenWags]

Description

After Ads have been disabled and then re-enabled, Ad notifications will not be shown until you restart Brave.

Steps to Reproduce

1. Clean install/profile.
2. Enable Rewards (Ads are also enabled)
3. Go to brave://rewards page
4. Disable Ads
5. Wait 30s or so, enable Ads.
6. Visit a site, wait until you see Browser state changed to idle in terminal then move the mouse.
7. No ad is shown. You get Notification not made: Confirmations not ready in terminal.
8. Give it another minute or so, try step 6 again. Same result. This will continue (you won't get Ads) until you restart Brave. Then you will start to see Ads again.

Actual result:

Ad notifications not shown after re-enabling Ads from panel on brave://rewards

Expected result:

Ad notifications should be shown after re-enabling Ads from panel.

Reproduces how often:

easily

Brave version (brave://version info)

Brave	0.63.55 Chromium: 74.0.3729.131 (Official Build) (64-bit)
Revision	518a41c1fa7ce1c8bb5e22346e82e42b4d76a96f-refs/branch-heads/3729@{#954}
OS	Mac OS X

Brave	0.64.75 Chromium: 74.0.3729.131 (Official Build) (64-bit)
Revision	518a41c1fa7ce1c8bb5e22346e82e42b4d76a96f-refs/branch-heads/3729@{#954}
OS	Mac OS X

Brave	0.65.92 Chromium: 74.0.3729.131 (Official Build) beta(64-bit)
Revision	518a41c1fa7ce1c8bb5e22346e82e42b4d76a96f-refs/branch-heads/3729@{#954}
OS	Mac OS X

Brave	0.66.63 Chromium: 74.0.3729.131 (Official Build) dev(64-bit)
Revision	518a41c1fa7ce1c8bb5e22346e82e42b4d76a96f-refs/branch-heads/3729@{#954}
OS	Mac OS X

Version/Channel Information:

• Can you reproduce this issue with the current release? yes
• Can you reproduce this issue with the beta channel? yes
• Can you reproduce this issue with the dev channel? yes
• Can you reproduce this issue with the nightly channel? unsure, but probably yes

Other Additional Information:

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

Miscellaneous Information:

reproduced by @srirambv
cc @jsecretan @tmancey

[tmancey]

@LaurenWags This issue was resolved by #4748