Add History.TopHostsVisitsByRank UMA metric.

components/history/core/browser/url_utils_unittest.cc

Index: components/history/core/browser/url_utils_unittest.cc
diff --git a/components/history/core/browser/url_utils_unittest.cc b/components/history/core/browser/url_utils_unittest.cc
index 184bd66552fbf5a1c4c982001cf0ca8d1cb58a43..77f8f1cbf1b2566520aa1d8104a00e77e0254f3a 100644
--- a/components/history/core/browser/url_utils_unittest.cc
+++ b/components/history/core/browser/url_utils_unittest.cc
@@ -126,6 +126,13 @@ TEST(HistoryUrlUtilsTest, ToggleHTTPAndHTTPS) {
             ToggleHTTPAndHTTPS(GURL("ftp://www.google.com/")));
 }
 
+TEST(HistoryUrlUtilsTest, HostForTopHosts) {
+  EXPECT_EQ("foo.com", HostForTopHosts(GURL("https://foo.com/bar")));
+  EXPECT_EQ("foo.com", HostForTopHosts(GURL("http://foo.com:999/bar")));
+  EXPECT_EQ("foo.com", HostForTopHosts(GURL("http://www.foo.com/bar")));
+  EXPECT_EQ("foo.com", HostForTopHosts(GURL("HtTP://WWw.FoO.cOM/BAR")));
+}
+
 }  // namespace
 
 }  // namespace history