Grant checks are now performed every 24 hours

[jasonrsadler]

Resolves brave/brave-browser#917

Ledger implementation: brave-intl/bat-native-ledger#160

Submitter Checklist:

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Verified that these changes build without errors on
  • Windows
  • macOS
  • Linux
• Verified that these changes pass automated tests (npm test brave_unit_tests && npm test brave_browser_tests) on
  • Windows
  • macOS
  • Linux
• Ran git rebase master (if needed).
• Ran git rebase -i to squash commits (if needed).
• Tagged reviewers and labelled the pull request as needed.
• Request a security/privacy review as needed.
• Add appropriate QA labels (QA/Yes or QA/No) to include the closed issue in milestone

Test Plan:

1. Start Brave using --vmodule=*rewards*=5 and enable rewards.
2. Quit Brave and restart
3. Ensure that grant check is not performed (view request in terminal)
4. Quit Brave.
5. Open ledger state and modify last_grant_fetch_stamp to be 24 hours (or more) in the past.
6. Start Brave and ensure that grant check is performed (view request in termainal)

1. Start Brave using --vmodule=*rewards*=5 and enable rewards.
2. Quit Brave and restart
3. Ensure that grant check is not performed (view request in terminal)
4. Start Brave and open Rewards page and ensure that grant check is performed.
5. Open ledger-state and verify that last_grant_fetch_stamp is reset to 24 hours since opening Rewards page.

Reviewer Checklist:

• New files have MPL-2.0 license header.
• Request a security/privacy review as needed.
• Adequate test coverage exists to prevent regressions
• Verify test plan is specified in PR before merging to source

[NejcZdovc]

master 2d027a6
0.57.x 1e33d8d
0.56.x 0365868