Do not deliver Brave Ad notifications if we do not have enough unblinded tokens

[tmancey]

Description

Steps to Reproduce

1. Deplete unblinded tokens to zero (and disable refill unblinded tokens endpoint using a proxy)

Actual result:

Ad notifications are shown and users are not rewarded

Expected result:

Ad notifications should not be shown

Reproduces how often:

Easily reproduced

Brave version (brave://version info)

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 nightly channel? 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:

[LaurenWags]

Verified passed with

Brave	1.15.69 Chromium: 86.0.4240.55 (Official Build) (x86_64)
Revision	a6d625ef6f7fe8ea0675f1cf759155a05ee1be40-refs/branch-heads/4240@{#953}
OS	macOS Version 10.14.6 (Build 18G3020)

Verified test plan from https://github.com/brave/internal/issues/731

Verified that ad is not shown when there are not enough unblinded tokens:

[660:775:1001/111008.251033:VERBOSE2:ads_impl.cc(1173)] You do not have enough unblinded tokens
[660:775:1001/111008.251102:VERBOSE1:ads_impl.cc(876)] Ad notification not shown: Not allowed based on history

Verified that after unblinded tokens are refilled, ads are shown.

---

Verification passed on

Brave | 1.15.69 Chromium: 86.0.4240.55 (Official Build) (64-bit)
-- | --
Revision | a6d625ef6f7fe8ea0675f1cf759155a05ee1be40-refs/branch-heads/4240@{#953}
OS | Windows 10 OS Version 1903 (Build 18362.1016)

• Verified test plan from https://github.com/brave/internal/issues/731
• Verified that ad is not shown when there are not enough unblinded tokens:

[16076:23492:1001/223941.601:VERBOSE2:ads_impl.cc(1173)] You do not have enough unblinded tokens
[16076:23492:1001/223941.601:VERBOSE1:ads_impl.cc(876)] Ad notification not shown: Not allowed based on history

• Verified that after unblinded tokens are refilled, ads are shown.

[16872:26480:1001/224609.760:VERBOSE1:ads_impl.cc(1113)] Ad notification shown:
  uuid: 2ebbc5eb-09ca-47fc-83ee-55e352713c2f
  parentUuid: 308b4474-30c4-4585-9936-c4186742d08f
  creativeInstanceId: b875ff4f-aa3f-4773-a79f-e8f0cd08bdc8
  creativeSetId: f706af3a-4cb9-4e85-bf6d-6259bd696d4e
  category: food & drink
  title: Hotel Deals Club
  body: Travel more, pay (much) less. Save up to 80% on hotels today.
  targetUrl: https://travala.com/
[16872:26480:1001/224609.760:VERBOSE1:ads_service_impl.cc(2046)] Timeout ad notification with uuid 2ebbc5eb-09ca-47fc-83ee-55e352713c2f in 120 seconds
[16872:26480:1001/224609.760:VERBOSE3:ad_notification_event_viewed.cc(30)] Viewed ad notification with uuid 2ebbc5eb-09ca-47fc-83ee-55e352713c2f and b875ff4f-aa3f-4773-a79f-e8f0cd08bdc8 creative instance id
[16872:26480:1001/224609.760:VERBOSE1:confirmations.cc(119)] Confirm ad:
  creativeInstanceId: b875ff4f-aa3f-4773-a79f-e8f0cd08bdc8
  creativeSetId: f706af3a-4cb9-4e85-bf6d-6259bd696d4e
  category: food & drink
  targetUrl: https://travala.com/
  geoTarget: IN
  confirmationType: view

---

Verification passed on

Brave	1.15.69 Chromium: 86.0.4240.55 (Official Build) (64-bit)
Revision	a6d625ef6f7fe8ea0675f1cf759155a05ee1be40-refs/branch-heads/4240@{#953}
OS	Ubuntu 18.04 LTS

Verified test plan from https://github.com/brave/internal/issues/731

Verified that ad is not shown when there are not enough unblinded tokens:

[12122:665:1001/191512.121344:VERBOSE2:ads_impl.cc(1173)] You do not have enough unblinded tokens
[12122:665:1001/191512.121401:VERBOSE1:ads_impl.cc(876)] Ad notification not shown: Not allowed based on history

Verified that after unblinded tokens are refilled, ads are shown.