Non-referral downloads should use generic refcode

[emerick]

Fixes brave/brave-browser#2547

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
• Verified that all lint errors/warnings are resolved (npm run lint)
• 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:

• Download a non-referral stub installer (i.e., no referral code embedded in its filename)

• Delete existing profile

• Run the installer

• After the installer completes, launch Brave and wait ~10 seconds

• Confirm that Local State file (e.g., /c/Users/emerick/AppData/Local/BraveSoftware/Brave-Browser-Development/User Data/Local State) contains "promo_code":"BRV001" entry

• Confirm with server team that daily ping for this run looked similar to this (in particular, ref is BRV001):

  https://laptop-updates.brave.com/1/usage/brave-core?platform=winx64-bc&channel=release&version=0.64.4&daily=true&weekly=true&monthly=true&first=true&w oi=2019-03-11&ref=BRV001

• Should also confirm that regular referral downloads continue to work as normal

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

[emerick]

@bbondy Two things to note here:

1. The default referral code will revert to none 90 days after first run, just like normal referral codes.
2. Since the referral code check is only performed on first run after install, pre-existing non-referral installations will continue to send none.

My reading of brave/brave-browser#2547 is that this is the expected/intended behavior, but if not please let me know!

[bbondy]

Yes reset after 90 days is expect. Thanks so much!

[bbondy]

Approving but wait for security sign off.

[diracdeltas]

if i'm not mistaken, this should be blocked on brave/vault-updater#90 and also https://github.com/brave/internal/issues/542#issuecomment-473574540, the latter of which i am working on

[fmarier]

@diracdeltas said she will take care of reviewing this.

[diracdeltas]

looks good to go as soon as brave/vault-updater#90 is closed