stats for arm64 on linux and windows

[mihaiplesa]

For https://github.com/brave/brave-browser/issues/6319 For https://github.com/brave/brave-browser/issues/11836

Submitter Checklist:

• [ ] I confirm that no security/privacy review is needed, or that I have requested one
• [ ] There is a ticket for my issue
• [ ] Used Github auto-closing keywords in the PR description above
• [ ] Wrote a good PR/commit description
• [ ] Squashed any review feedback or "fixup" commits before merge, so that history is a record of what happened in the repo, not your PR
• [ ] Added appropriate labels (QA/Yes or QA/No; release-notes/include or release-notes/exclude; OS/...) to the associated issue
• [ ] Checked the PR locally: npm run test -- brave_browser_tests, npm run test -- brave_unit_tests, npm run lint, npm run gn_check, npm run tslint
• [ ] Ran git rebase master (if needed)

Reviewer Checklist:

• [ ] A security review is not needed, or a link to one is included in the PR description
• [ ] New files have MPL-2.0 license header
• [ ] Adequate test coverage exists to prevent regressions
• [ ] Major classes, functions and non-trivial code blocks are well-commented
• [ ] Changes in component dependencies are properly reflected in gn
• [ ] Code follows the style guide
• [ ] Test plan is specified in PR before merging

After-merge Checklist:

• [ ] The associated issue milestone is set to the smallest version that the changes has landed on
• [ ] All relevant documentation has been updated, for instance:
  • [ ] https://github.com/brave/brave-browser/wiki/Deviations-from-Chromium-(features-we-disable-or-remove)
  • [ ] https://github.com/brave/brave-browser/wiki/Proxy-redirected-URLs
  • [ ] https://github.com/brave/brave-browser/wiki/Fingerprinting-Protections
  • [ ] https://github.com/brave/brave-browser/wiki/Brave%E2%80%99s-Use-of-Referral-Codes
  • [ ] https://github.com/brave/brave-browser/wiki/Custom-Headers
  • [ ] https://github.com/brave/brave-browser/wiki/Web-Compatibility-Exceptions-in-Brave
  • [ ] https://github.com/brave/brave-browser/wiki/QA-Guide
  • [ ] https://github.com/brave/brave-browser/wiki/P3A

Test Plan:

[porteron]

@mihaiplesa We will need to update our platform mappings in the analytics system to make sure we are picking up these new platform types. I'll address today. @aekeus please advise.

[mihaiplesa]

@porteron any trouble if this goes in first? Also, I can prepare the other PRs but will hold and wait for a decision.

[aekeus]

I would be more comfortable holding until we have the mappings in stats, but will leave the final go/no go with @porteron.

[mherrmann]

This could be tested by inspecting the log output of BraveP3AService::InitMessageMeta. It logs the platform identifier that we modified here.

[mherrmann]

How about

#if defined(ARCH_CPU_ARM64)
  return "winarm64-bc";
#else
  if (base::SysInfo::OperatingSystemArchitecture() == "x86")
    return "winia32-bc";
  else
    return "winx64-bc";
#endif