[Autofill] Use AutofillClock::Now in autofill_tets_utils

Using AutofillClock::Now was thought to be the cause of the flakiness of
the credit card related tests and was replaced with base::Time::Now
in [1]. However, the tests are still flaky, so this CL returns using
AutofillClock::Now, which allows having deterministic clock in tests.

[1]https://chromium-review.googlesource.com/c/chromium/src/+/2428986

Bug: 1108232
Change-Id: I052bb17926eda5537b7223f4d6c2c08432e3c215
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2613032Reviewed-by: Christoph Schwering <schwering@google.com>
Reviewed-by: Matthias Körber <koerber@google.com>
Commit-Queue: Elizabeth Popova <lizapopova@google.com>
Cr-Commit-Position: refs/heads/master@{#842518}

components/autofill/core/browser/autofill_test_utils.cc

@@ -875,26 +875,22 @@ std::string ObfuscatedCardDigitsAsUTF8(const std::string& str) {
 
 std::string NextMonth() {
   base::Time::Exploded now;
-  // Using AutofillClock here might cause test flakiness. See crbug/1108232.
-  base::Time::Now().LocalExplode(&now);
+  AutofillClock::Now().LocalExplode(&now);
   return base::StringPrintf("%02d", now.month % 12 + 1);
 }
 std::string LastYear() {
   base::Time::Exploded now;
-  // Using AutofillClock here might cause test flakiness. See crbug/1108232.
-  base::Time::Now().LocalExplode(&now);
+  AutofillClock::Now().LocalExplode(&now);
   return base::NumberToString(now.year - 1);
 }
 std::string NextYear() {
   base::Time::Exploded now;
-  // Using AutofillClock here might cause test flakiness. See crbug/1108232.
-  base::Time::Now().LocalExplode(&now);
+  AutofillClock::Now().LocalExplode(&now);
   return base::NumberToString(now.year + 1);
 }
 std::string TenYearsFromNow() {
   base::Time::Exploded now;
-  // Using AutofillClock here might cause test flakiness. See crbug/1108232.
-  base::Time::Now().LocalExplode(&now);
+  AutofillClock::Now().LocalExplode(&now);
   return base::NumberToString(now.year + 10);
 }