Ads count isn't increasing for upgrade path

[srirambv]

Description

Ads count isn't increasing for an upgrade path

Steps to Reproduce

1. Install an older nightly build
2. Trigger an ad
3. Wait for the token to be cashed in
4. Upgrade to the new nightly build
5. Ensure you have unpaid tokens
6. Ads count isn't increased after upgrade only pending amount is increased

Actual result:

Ads count isn't increasing for upgrade path

Expected result:

Ads count should incease

Reproduces how often:

Easy

Brave version (brave://version info)

Miscellaneous Information:

cc: @tmancey @LaurenWags

[srirambv]

• Verification passed on

Brave	0.66.99 Chromium: 75.0.3770.100 (Official Build) (64-bit)
Revision	cd0b15c8b6a4e70c44e27f35c37a4029bad3e3b0-refs/branch-heads/3770@{#1033}
OS	Windows 10 OS Version 1809 (Build 17763.557)

• Verified steps from the original issue

• Verified before upgrade timestamp was in webkit standard 13xxxxxxxx
  

• Verified post upgrade timestamp was updated to epoch standard 15xxxxxxxx
  

• Verified tokens are cashed out correctly and ad notifications received show the correct count post upgrade

• Verification passed on

Brave	0.66.99 Chromium: 75.0.3770.100 (Official Build) (64-bit)
Revision	cd0b15c8b6a4e70c44e27f35c37a4029bad3e3b0-refs/branch-heads/3770@{#1033}
OS	Linux

• Verified steps from the original issue
• Verified before upgrade timestamp was in webkit standard 13xxxxxxxx
  
• Verified post upgrade timestamp was updated to epoch standard 15xxxxxxxx
  
• Verified tokens are cashed out correctly and ad notifications received show the correct count post upgrade

Verified passed with

Brave	0.66.99 Chromium: 75.0.3770.100 (Official Build) (64-bit)
Revision	cd0b15c8b6a4e70c44e27f35c37a4029bad3e3b0-refs/branch-heads/3770@{#1033}
OS	Mac OS X

Used these STR:

1. Clean install 0.65.121 on Release
2. Enable rewards and view an ad
3. Close browser and check date time stamps in confirmations.json
4. Verify they are using webkit standard (start with 13xxx)
5. Redeem tokens on server
6. Confirm payout on console logs
7. View two more ads. Est BAT is 0.15, payment is monthly, 5th, and ads viewed is 3 - all as expected. Close Brave.
8. Open confirmations.json and verify that you have additional entries in transactions for the newly viewed ads as well as have corresponding unblinded_payment_tokens. All are using webkit timestamp.
9. Relaunched browser with 0.66.99
10. est pending rewards still 0.15 BAT, next payment date Jul 5 and ad notifications received this month is 3. All as expected.
11. Close and relaunch Brave.
12. Verify you see getpaymentbalance and ongetpaymentbalance calls in logs.
13. View another Ad.
14. Verify est pending bat increases to 0.20 and ads viewed increments to 4. next payment date remains july 5. All as expected.