Brave now builds if brave_rewards_enabled is false

[jasonrsadler]

Fixes brave/brave-browser#4069

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 && npm run test-security) 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
• Public documentation has been updated as necessary. 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-Protection-Mode
  • 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-issues-with-tracking-protection

Test Plan:

1. Modify components/brave_rewards/browser/buildflags/buildflags.gni from

import("//build/config/features.gni")

declare_args() {
  brave_rewards_enabled = is_mac || is_linux || is_win || is_android
}

to

import("//build/config/features.gni")

declare_args() {
  brave_rewards_enabled = false
}

2. Run npm run build and make sure build is successful
3. Run npm start and make sure Brave runs with Rewards disabled without errors
4. Run npm run test -- brave_unit_tests && npm run test -- brave_browser_tests and make sure all tests pass
5. Change buildflags.gni back to original state and repeat steps 2-4 with step 3 ensuring that Rewards functions correctly

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

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.

[simonhong]

nit: There is an implicit convention in chromium about header inclusion in guard.
Usually they are positioned at last like below.

#include "ui/views/widget/tooltip_manager.h"
#include "ui/views/widget/widget.h"

#if defined(OS_WIN)
#include "base/win/scoped_gdi_object.h"
#include "ui/native_theme/native_theme_win.h"
#endif

[jasonrsadler]

Done.

[simonhong]

ditto

[jasonrsadler]

Done.

[emerick]

LGTM

[sebionofrei]

FYI, this is no longer working :)

[tmancey]

@sebionofrei can you please raise a new issue, thank you