Enable ExpireHistoryTest.DeleteURLAndFavicon

This test failed near the end of month in 2009. There was a suspicion
that sqlite might need to be updated and it was updated in 2011.

I couldn't reproduce the failure by manually setting my time to Jan 31
5:35PM PST, so maybe the reason behind the failure was fixed within the
last 10 years.

Bug: 15724
Change-Id: I72cc042b46af2b11d6f7679a5f76c0d2b0c4b575
Reviewed-on: https://chromium-review.googlesource.com/c/1449597
Auto-Submit: Christian Dullweber <dullweber@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#628446}

components/history/core/browser/expire_history_backend_unittest.cc

@@ -451,8 +451,9 @@ bool ExpireHistoryTest::IsStringInFile(const base::FilePath& filename,
 
 // Deletes a URL with a favicon that it is the last referencer of, so that it
 // should also get deleted.
-// Fails near end of month. http://crbug.com/43586
-TEST_F(ExpireHistoryTest, DISABLED_DeleteURLAndFavicon) {
+// This test failed near end of month.
+// Please comment on http://crbug.com/15724 if it fails again.
+TEST_F(ExpireHistoryTest, DeleteURLAndFavicon) {
   URLID url_ids[3];
   base::Time visit_times[4];
   AddExampleData(url_ids, visit_times);