Revert "Make timezone unittest less dependent on environment"

This reverts commit b9e3249.

Reason for revert: breaks MSAN base_unittests: https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Linux%20MSan%20Tests/14315

[ RUN      ] TimezoneTest.CountryCodeForTimezones
==12431==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x55bd41fbd0c1 in icu_63::TZEnumeration::snext(UErrorCode&) ./../../third_party/icu/source/i18n/timezone.cpp:931:31
    #1 0x55bd3e8c9c45 in base::(anonymous namespace)::TimezoneTest_CountryCodeForTimezones_Test::TestBody() ./../../base/i18n/timezone_unittest.cc:20:58
    #2 0x55bd414ee9a0 in HandleExceptionsInMethodIfSupported<testing::Test, void> ./../../third_party/googletest/src/googletest/src/gtest.cc:0:0
    #3 0x55bd414ee9a0 in testing::Test::Run() ./../../third_party/googletest/src/googletest/src/gtest.cc:2522:0
    #4 0x55bd414f24d3 in testing::TestInfo::Run() ./../../third_party/googletest/src/googletest/src/gtest.cc:2703:11
    #5 0x55bd414f40e9 in testing::TestCase::Run() ./../../third_party/googletest/src/googletest/src/gtest.cc:2825:28
    #6 0x55bd4152e9d9 in testing::internal::UnitTestImpl::RunAllTests() ./../../third_party/googletest/src/googletest/src/gtest.cc:5227:43
    #7 0x55bd4152d2c8 in HandleExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool> ./../../third_party/googletest/src/googletest/src/gtest.cc:0:0
    #8 0x55bd4152d2c8 in testing::UnitTest::Run() ./../../third_party/googletest/src/googletest/src/gtest.cc:4835:0
    #9 0x55bd41b8f42a in RUN_ALL_TESTS ./../../third_party/googletest/src/googletest/include/gtest/gtest.h:2369:46
    #10 0x55bd41b8f42a in base::TestSuite::Run() ./../../base/test/test_suite.cc:294:0
    #11 0x55bd41bb9d49 in Run ./../../base/callback.h:99:12
    #12 0x55bd41bb9d49 in base::(anonymous namespace)::LaunchUnitTestsInternal(base::OnceCallback<int ()>, unsigned long, int, bool, base::OnceCallback<void ()>) ./../../base/test/launcher/unit_test_launcher.cc:225:0
    #13 0x55bd41bb94a7 in base::LaunchUnitTests(int, char**, base::OnceCallback<int ()>) ./../../base/test/launcher/unit_test_launcher.cc:575:10
    #14 0x55bd41b522a8 in main ./../../base/test/run_all_base_unittests.cc:12:10
    #15 0x7f1906a7ef44 in __libc_start_main ??:0:0
    #16 0x55bd3dc8d029 in _start ??:0:0


Original change's description:
> Make timezone unittest less dependent on environment
> 
> Instead of only testing the current default timezone, test all
> timezones.
> 
> Noticed this while looking into crbug.com/920094
> 
> Bug: none
> Change-Id: Ida24c063cefb384037fc77c3673ff2d73ab7354f
> Reviewed-on: https://chromium-review.googlesource.com/c/1407437
> Reviewed-by: Jungshik Shin <jshin@chromium.org>
> Commit-Queue: Evan Stade <estade@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#622505}

TBR=thestig@chromium.org,estade@chromium.org,jshin@chromium.org

Change-Id: I86d37bbe6749f3f8a5b81bf3967755e43f441161
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: none
Reviewed-on: https://chromium-review.googlesource.com/c/1409815
Reviewed-by: Jeremy Roman <jbroman@chromium.org>
Commit-Queue: Jeremy Roman <jbroman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#622600}

base/i18n/timezone_unittest.cc

@@ -5,34 +5,22 @@
 #include "base/i18n/timezone.h"
 
 #include "testing/gtest/include/gtest/gtest.h"
-#include "third_party/icu/source/common/unicode/strenum.h"
-#include "third_party/icu/source/common/unicode/unistr.h"
-#include "third_party/icu/source/i18n/unicode/timezone.h"
 
 namespace base {
 namespace {
 
-TEST(TimezoneTest, CountryCodeForTimezones) {
-  std::unique_ptr<icu::StringEnumeration> timezones(
-      icu::TimeZone::createEnumeration());
-
-  UErrorCode status;
-  while (const icu::UnicodeString* timezone = timezones->snext(status)) {
-    icu::TimeZone::adoptDefault(icu::TimeZone::createTimeZone(*timezone));
-
-    std::string country_code = CountryCodeForCurrentTimezone();
-    // On some systems (such as Android or some flavors of Linux), ICU may come
-    // up empty. With https://chromium-review.googlesource.com/c/512282/ , ICU
-    // will not fail any more. See also
-    // http://bugs.icu-project.org/trac/ticket/13208 . Even with that, ICU
-    // returns '001' (world) for region-agnostic timezones such as Etc/UTC and
-    // |CountryCodeForCurrentTimezone| returns an empty string so that the next
-    // fallback can be tried by a customer.
-    if (!country_code.empty())
-      EXPECT_EQ(2U, country_code.size()) << "country_code = " << country_code;
-  }
-
-  icu::TimeZone::adoptDefault(nullptr);
+TEST(TimezoneTest, CountryCodeForCurrentTimezone) {
+  std::string country_code = CountryCodeForCurrentTimezone();
+  // On some systems (such as Android or some flavors of Linux), ICU may come up
+  // empty. With https://chromium-review.googlesource.com/c/512282/ , ICU will
+  // not fail any more. See also http://bugs.icu-project.org/trac/ticket/13208 .
+  // Even with that, ICU returns '001' (world) for region-agnostic timezones
+  // such as Etc/UTC and |CountryCodeForCurrentTimezone| returns an empty
+  // string so that the next fallback can be tried by a customer.
+  // TODO(jshin): Revise this to test for actual timezones using
+  // use ScopedRestoreICUDefaultTimezone.
+  if (!country_code.empty())
+    EXPECT_EQ(2U, country_code.size()) << "country_code = " << country_code;
 }
 
 }  // namespace