Add Brave Rewards browser tests

[emerick]

Fix brave/brave-browser#3161
Requires brave/brave-ui#417

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:

npm test brave_unit_tests && npm test brave_browser_tests

Individual tests are described in detail in:
https://docs.google.com/document/d/1Mwu9STT-AYHVP7mgbmQkOXgYkdmKrPJTj8bYuLVK6nc

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]

@NejcZdovc Officially ready for review!

[simonhong]

Just left some comments.
Passing to @NejcZdovc for the rest.

[NejcZdovc]

@emerick can you please rebase

[emerick]

@NejcZdovc Sure, should be all set now.

[NejcZdovc]

[70257:775:0412/175301.809834:INFO:CONSOLE(2171)] "[object Object]", source: chrome://rewards/brave_rewards.bundle.js (2171)
../../brave/components/brave_rewards/browser/rewards_service_browsertest.cc:693: Failure
Expected: (js_result.ExtractString().find(balance)) != (std::string::npos), actual: 18446744073709551615 vs 18446744073709551615
Stack trace:
0   libbase.dylib                       0x0000000131bc49ad base::debug::StackTrace::StackTrace(unsigned long) + 29
1   libbase.dylib                       0x0000000131bc4985 base::debug::StackTrace::StackTrace() + 37
2   brave_browser_tests                 0x000000010a93be4a StackTraceGetter::CurrentStackTrace(int, int) + 90
3   brave_browser_tests                 0x000000010a94c267 testing::internal::UnitTestImpl::CurrentOsStackTraceExceptTop(int) + 71
4   brave_browser_tests                 0x000000010a94bd41 testing::internal::AssertHelper::operator=(testing::Message const&) const + 145
5   brave_browser_tests                 0x0000000107bf6008 BraveRewardsBrowserTest::TipPublisher(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, bool, bool) + 4104
6   brave_browser_tests                 0x0000000107bf4fab BraveRewardsBrowserTest_TipVerifiedPublisher_Test::RunTestOnMainThread() + 123
7   brave_browser_tests                 0x00000001108e9d17 content::BrowserTestBase::ProxyRunTestOnMainThreadLoop() + 743
8   brave_browser_tests                 0x00000001108ec34d void base::internal::FunctorTraits<void (content::BrowserTestBase::*)(), void>::Invoke<void (content::BrowserTestBase::*)(), content::BrowserTestBase*>(void (content::BrowserTestBase::*)(), content::BrowserTestBase*&&) + 125
9   brave_browser_tests                 0x00000001108ec251 void base::internal::InvokeHelper<false, void>::MakeItSo<void (content::BrowserTestBase::* const&)(), content::BrowserTestBase*>(void (content::BrowserTestBase::* const&)(), content::BrowserTestBase*&&) + 81
10  brave_browser_tests                 0x00000001108ec1d5 void base::internal::Invoker<base::internal::BindState<void (content::BrowserTestBase::*)(), base::internal::UnretainedWrapper<content::BrowserTestBase> >, void ()>::RunImpl<void (content::BrowserTestBase::* const&)(), std::__1::tuple<base::internal::UnretainedWrapper<content::BrowserTestBase> > const&, 0ul>(void (content::BrowserTestBase::* const&)(), std::__1::tuple<base::internal::UnretainedWrapper<content::BrowserTestBase> > const&, std::__1::integer_sequence<unsigned long, 0ul>) + 85
11  brave_browser_tests                 0x00000001108ec0fc base::internal::Invoker<base::internal::BindState<void (content::BrowserTestBase::*)(), base::internal::UnretainedWrapper<content::BrowserTestBase> >, void ()>::Run(base::internal::BindStateBase*) + 44
12  brave_browser_tests                 0x0000000108277c6d base::RepeatingCallback<void ()>::Run() const & + 61
13  brave_browser_tests                 0x000000010ef5d4ae ChromeBrowserMainParts::PreMainMessageLoopRunImpl() + 4974
14  brave_browser_tests                 0x000000010ef5c0a1 ChromeBrowserMainParts::PreMainMessageLoopRun() + 193
15  libcontent.dylib                    0x0000000140c65163 content::BrowserMainLoop::PreMainMessageLoopRun() + 243
16  libcontent.dylib                    0x0000000140c6ef9d int base::internal::FunctorTraits<int (content::BrowserMainLoop::*)(), void>::Invoke<int (content::BrowserMainLoop::*)(), content::BrowserMainLoop*>(int (content::BrowserMainLoop::*)(), content::BrowserMainLoop*&&) + 125
17  libcontent.dylib                    0x0000000140c6eea1 int base::internal::InvokeHelper<false, int>::MakeItSo<int (content::BrowserMainLoop::* const&)(), content::BrowserMainLoop*>(int (content::BrowserMainLoop::* const&)(), content::BrowserMainLoop*&&) + 81
18  libcontent.dylib                    0x0000000140c6ee25 int base::internal::Invoker<base::internal::BindState<int (content::BrowserMainLoop::*)(), base::internal::UnretainedWrapper<content::BrowserMainLoop> >, int ()>::RunImpl<int (content::BrowserMainLoop::* const&)(), std::__1::tuple<base::internal::UnretainedWrapper<content::BrowserMainLoop> > const&, 0ul>(int (content::BrowserMainLoop::* const&)(), std::__1::tuple<base::internal::UnretainedWrapper<content::BrowserMainLoop> > const&, std::__1::integer_sequence<unsigned long, 0ul>) + 85
19  libcontent.dylib                    0x0000000140c6ed1c base::internal::Invoker<base::internal::BindState<int (content::BrowserMainLoop::*)(), base::internal::UnretainedWrapper<content::BrowserMainLoop> >, int ()>::Run(base::internal::BindStateBase*) + 44
20  libcontent.dylib                    0x00000001415ff07d base::RepeatingCallback<int ()>::Run() const & + 61
21  libcontent.dylib                    0x0000000141f44fbd content::StartupTaskRunner::RunAllTasksNow() + 109
22  libcontent.dylib                    0x0000000140c634ba content::BrowserMainLoop::CreateStartupTasks() + 1370
23  libcontent.dylib                    0x0000000140c75614 content::BrowserMainRunnerImpl::Initialize(content::MainFunctionParams const&) + 1524
24  libcontent.dylib                    0x0000000140c5f38f content::BrowserMain(content::MainFunctionParams const&) + 143
25  libcontent.dylib                    0x00000001435f1376 content::RunBrowserProcessMain(content::MainFunctionParams const&, content::ContentMainDelegate*) + 134
26  libcontent.dylib                    0x00000001435f29d8 content::ContentMainRunnerImpl::RunServiceManager(content::MainFunctionParams&, bool) + 1240
27  libcontent.dylib                    0x00000001435f2418 content::ContentMainRunnerImpl::Run(bool) + 600
28  libcontent.dylib                    0x00000001435eee19 content::ContentServiceManagerMainDelegate::RunEmbedderProcess() + 57
29  libembedder.dylib                   0x000000017f67b0a7 service_manager::Main(service_manager::MainParams const&) + 1607
30  libcontent.dylib                    0x00000001435f12a9 content::ContentMain(content::ContentMainParams const&) + 89
31  brave_browser_tests                 0x00000001108e9795 content::BrowserTestBase::SetUp() + 2325